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2016 2008 CAPS NCS Geometry Gr 12 Memo 14 July

Grade 12 Mathematics study guide from the 2016, 45 pages. Read online or get the free PDF download.

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Western Cape Education Department Examination Preparation Learning Resource 2016 GEOMETRY MEMORANDUM MATHEMATICS Grade 12 Razzia Ebrahim Senior Curriculum Planner for Mathematics E-mail: Razzia.Ebrahim@wced.info Website: http://www.wcedcurriculum.westerncape.gov.za/index.php/component/jdownloads/category/1835- grade-12?Itemid=-1 Website: http://wcedeportal.co.za Tel: 021 467 2617 Cell: 083 708 0448
Index Page 1. 2016 Feb-March Paper 2 3–6 2. 2015 November Paper 2 7–9 3. 2015 June Paper 2 10 – 12 4. 2015 Feb-March Paper 2 13 – 16 5. 2014 November Paper 2 17 – 21 6. 2014 Exemplar Paper 2 22 – 24 7. 2013 November Paper 3 25 – 27 8. 2012 November Paper 3 28 – 31 9. 2011 November Paper 3 32 – 34 10. 2010 November Paper 3 35 – 38 11. 2009 November Paper 3 39 – 42 12. 2008 November Paper 3 43 – 45 2
Mathematics/P2/Wiskunde V2 DBE/ Feb.–Mar./Feb.–Mrt. 2016 NSC/NSC – Memorandum QUESTION/VRAAG 9 A 1 2 3 B 1 F O 2 3 D 1 2 2 3 1 3 C G E 9.1 ABCD is a ||m [diags of quad bisect each other/ R hoekl v vh halveer mekaar] (1) 9.2 ED FE S  R = [Prop Th/Eweredigh st; DF | | BA] DB AF ED GE S  R = [Prop Th/Eweredigh st; DG | | BC] DB CG (4) 9.3 FE GE S = [proved/bewys] AF CG ∴AC | | FG [line divides two sides of ∆ in prop/  S R lyn verdeel 2 sye van ∆ eweredig] S Ĉ 2 = F̂2 [alt/verw ∠s/e; AC | | FG] S Â 1 = Ĉ 2 [alt/verw ∠s/e; AB | | CD] (5) ∴ Â 1 = F̂2 9.4 Â 1 = Â 2 [diags of rhombus/hoekl v ruit] S Â 2 = F̂2 [ Â 1 = F̂2 ] S ∴ ACGF = cyc quad/kdvh [∠s in the same seg =/ R ∠e in dies segm =] (3) OR/OF Ĉ 2 = Â 2 [∠s opp equal sides of rhombus/ S ∠e to gelyke sye v ruit] Â 2 = Ĝ 2 [alt/verw-∠s/e; AC | | FG] S ∴ Ĉ 2 = Ĝ 2 ∴ ACGF is a cyc quad/kdvh [∠s in the same seg =/ ∠e in dies segm =] R (3) [13] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 3
Mathematics/P2/Wiskunde V2 DBE/ Feb.–Mar./Feb.–Mrt. 2016 NSC/NSC – Memorandum QUESTION/VRAAG 10 A P 10.1 D E Q R B C 10.1.1 In ∆ADE and/en ∆PQR: AD = PQ [construction/konstr] all/al 3 S’s/e  = P̂ [given/gegee] AE = PR [construction/konstr] ∴∆ADE ≡ ∆PQR [S∠S] reason/rede (2) 10.1.2 AD̂E = Q̂ [∆s ≡ ∴ corres/ooreenk ∠s/e =]  AD̂E = Q̂ But B̂ = Q̂ [given/gegee] ∴ AD̂E = B̂  AD̂E = B̂ ∴ DE | | BC [corres/ooreenk ∠s/e =] reason/rede (3) 10.1.3 AB AC = [Prop Th/Eweredigh st; DE | | BC] S/R AD AE But/Maar AD = PQ and/en AE = PR [construction/konstr] S AB AC ∴ PQ = PR (2) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 4
Mathematics/P2/Wiskunde V2 DBE/ Feb.–Mar./Feb.–Mrt. 2016 NSC/NSC – Memorandum 10.2 R T O 2 2 1 1 2 P V 1 1 S 10.2.1 line from centre to midpt of chord/lyn van midpt na midpt van answ/antw koord (1) 10.2.2 OP | | VS [Midpt Theorem/Midpt-stelling] S  R In ∆ROP and/en ∆RVS: R̂ = R̂ [common/gemeen] S Ô 2 = V̂ [corresp/ooreenk ∠s/e; OP | | VS] S & ∠;∠;∠ OR/OF ∴∆ROP | | | ∆RVS [∠,∠,∠] 3 angles/hoeke (4) OR/OF In ∆ROP and/en ∆RVS: P̂2 = VŜR [corresponding ∠s/ ooreenkomstige ∠'e] S  R R̂ = R̂ [common/gemeen] S ∴∆ROP | | | ∆RVS [∠,∠,∠] S & ∠;∠;∠ OR/OF 3 angles/hoeke (4) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 5
Mathematics/P2/Wiskunde V2 DBE/ Feb.–Mar./Feb.–Mrt. 2016 NSC/NSC – Memorandum 10.2.3 In ∆RVS and/en ∆RST: VŜR = ST̂R = 90° [∠ in semi-circle/∠ in halfsirkel] S  R R̂ is common/gemeen S & ∠;∠;∠ V̂ = TŜR OR/OF ∴∆RVS | | | ∆RST [∠,∠,∠] 3 angles/hoeke (3) 10.2.4 In ∆RTS and/en ∆STV: ∆RTS & ∆STV RT̂S = VT̂S = 90° [∠ s on straight line/∠e op rt lyn] S R̂ = 90° – TŜR S = TŜV S (with TŜR = V̂ justification/met ∴∆RTS | | | ∆STV [∠,∠,∠] motivering) RT TS ∴ = ∆RTS | | | ∆STV ST VT ∴ ST 2 = VT.TR ratio/verh (6) [21] Copyright reserved/Kopiereg voorbehou 6
Mathematics/P2/Wiskunde/V2 DBE/November 2015 NSC/NSS – Memorandum QUESTION/VRAAG 10 B 17 E 8 C F D A 10.1 BD̂C = 90° [∠ in semi circle/∠ in halfsirkel] S DC2 = 172 – 82 [Th of/stelling v Pythagoras]  using/gebruik = 225 Pyth korrek/ correctly ∴ DC = 15  answ/antw (3) 10.2.1 CF CE = [line | | one side of ∆/lyn | | een sy van ∆]  S/R CD CB CF 1 ∴ =  subst correctly/ 15 4 korrek ∴ CF = 3,75  answ/antw (3) 10.2.2 In ∆BAC and/en ∆ FEC: AB̂C = 90° [tan ⊥ diameter/raakl ⊥ middellyn] SR EF̂C = 90° [corresp ∠s/ooreenk ∠e; EF| |BD]  S/R Ĉ = Ĉ [common/gemeen] S ∴ ∆BAC | | | ∆ FEC [∠∠∠] R (5) OR/OF In ∆BAC and ∆ FEC: AB̂C = 90° [tan ⊥ diameter/raakl ⊥ middellyn] SR EF̂C = 90° [corresp ∠s/ooreenk ∠e; EF| |BD]  S/R Ĉ = Ĉ [common/gemeen] S BÂC = FÊC [∠ sum in ∆/∠ som van ∆] S ∴ ∆BAC | | | ∆ FEC (5) OR/OF Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 7
Mathematics/P2/Wiskunde/V2 DBE/November 2015 NSC/NSS – Memorandum ABEF = cyc quad/ kdvh [opp ∠s of quad supp/tos∠e v vh suppl)] ∴ FÊC = Â [ext ∠ of cyc quad/buite ∠ v kdvh] SR In ∆BAC and/en ∆ FEC:  S/R FÊC = Â [proven/bewys] Ĉ = Ĉ [common/gemeen] BÂC = FÊC [∠ sum in ∆/∠ som van ∆] S ∴ ∆BAC | | | ∆ FEC S (5) OR/OF ABEF = cyc quad/ kdvh [opp ∠s of quad supp/tos∠ SR e v vh suppl)]  S/R ∴ FÊC = Â [ext ∠ of cyc quad/buite ∠ v kdvh] In ∆BAC and ∆ FEC: FÊC = Â [proven/bewys] S Ĉ = Ĉ [common/gemeen] R ∴ ∆BAC | | | ∆ FEC [∠∠∠] (5) 10.2.3 1  length of/lengte v EC = × 17 = 4,25 4 EC AC BC = [||| ∆s/e] EC FC S AC 17 =  subst correctly/ 4,25 3,75 korrek 4 ∴AC = 19,27 or/of 19  answ/antw 15 (4) OR/OF CF BC cos Ĉ = =  correct ratios/ CE AC korrekte verh's 3,75 17 ∴ =  subst correctly/ 4,25 AC korrek 4  answ/antw ∴ AC = 19,27 or/of 19 15 (4) 10.2.4 AC is diameter of the circle [chord subtends 90° ]  S/R AC is middellyn van die sirkel [koord onderspan 90°] 1 19  answ/antw ∴radius = × 19,27 = 9,63 or/of 9 2 30 (2) [17] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 8
Mathematics/P2/Wiskunde/V2 DBE/November 2015 NSC/NSS – Memorandum QUESTION/VRAAG 11 11.1 equiangular or similar/gelykhoekig of gelykvormig  answ/antw (1) P • 2 1,5 ♦ M ♠ 2,5 K ♦ 1,25 1 ♠ R • 0,75 N ♦ Q 11.2.1 KP 1,5 PM 2 KM 2,5 = =2 ; = =2 ; = =2 all 3 statements/ RN 0,75 NM 1 RM 1.25 al 3 bewerings KP PM KM ∴ = = RN NM RM ∴ ∆KPM | | | ∆RNM [Sides of ∆ in prop/sye v ∆ eweredig]  R (3) OR/OF OR/OF RN 0,75 1 NM 1 RM 1,25 1 = = ; = ; = = all 3 statements/ KP 1,5 2 PM 2 KM 2,5 2 al 3 bewerings RN NM RM ∴ = = KP PM KM ∴ ∆KPM | | | ∆RNM [Sides of ∆ in prop/sye v ∆ eweredig]  R (3) 11.2.2 PK̂M = R̂ S ∴ P̂ is common/gemeen ∴ ∆RPQ | | | ∆KPM [∠∠∠]  ∆RPQ|||∆KPM RP RQ S = [||| ∆s] KP KM 3,25 RQ  subst correctly/ ∴ = 1,5 2,5 korrek 2,5 × 3,25 5 5 ∴ RQ = = 5,42 or 5  RQ = 5 1,5 12 12 2 ∴ NQ = 5,42 – 0,75 = 4,67 or 4  NQ = answ/antw 3 (6) [10] Copyright reserved/Kopiereg voorbehou 9
Mathematics/P2/Wiskunde V2 DBE/2015 NSCNSS – Memorandum QUESTION/VRAAG 10 10.1 then the line is parallel to the third side/is die lyn ewewydig aan S die derde sy. (1) B F D C A 12 E 8 10.2.1 AE 12 3 S = = AC 20 5 AD 3 = AF 5 AE AD ∴ = S AC AF ∴ DE || FC (line divides two sides of ∆ in prop/ R lyn verdeel twee sye v ∆ in dieselfde verh) (3) 10.2.2 BF 8 = (prop theorem/eweredigh st; BC || FE)  S/R BA 20 8 ∴ BF = (14)  substitute 14/ 20 stel 14 in 28 3 ∴ BF = OR/OF FB = 5 OR/OF FB = 5,6  answer/antw 5 5 (3) [7] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 10
Mathematics/P2/Wiskunde V2 DBE/2015 NSCNSS – Memorandum B D 1 2 1 C 2 1 2 E 1 2 A P 11.2.1 DĈA = 2 x (EC bisector) P̂ = x (∠ at centre = 2 ×∠ at circumference/ SR midpts∠ = 2 × omtreks∠) Â 1 = P̂ = x (tangent-chord theorem/rkl-kd st) SR In ∆BAD and ∆BCE: B̂ = B̂ (common/gemeen) S Â1 = Ĉ1 (proven above)  S(with justification) ∴∆BAD | | | ∆BCE (∠∠∠) R (7) OR/OF DĈA = 2 x (EC bisector) P̂ = x (∠ at centre = 2 ×∠ at circumference/ SR midpts∠ = 2 × omtreks∠) Â 1 = P̂ = x (tangent-chord theorem/rkl-kd st) SR In ∆BAD and ∆BCE: B̂ = B̂ (common/gemeen) S Â1 = Ĉ1 (proven above)  S(with justification) D̂1 = Ê 1 S ∴∆BAD | | | ∆BCE (7) Copyright reserved Please turn over/Blaai om asseblief 11
Mathematics/P2/Wiskunde V2 DBE/2015 NSCNSS – Memorandum 11.2.2(a) BÂC = 90° (tangent/raakl ⊥ radius) R ∴BC2 = 82+ 62 = 100 (Pythagoras theorem/stelling)  substitution into BC = 10 Pyth theorem AC = DC = 6 (radii)  BC = 10 ∴ BD = 10 – 6 = 4 units/eenhede  DC = 6  BD = 4 (5) 11.2.2(b) BA BD S = (∆BAD | | | ∆BCE) BC BE 8 4  substitution/ ∴ = 10 BE substitusie ∴ BE = 5 units/eenhede  BE = 5 (3) 11.2.2(c) AE = 3 In ∆ACE: 3  correct trig ratio/ tan x = korrekte trigvh 6  correct trig eq/ ∴x = 26,57° korrekte trigvgl  answer/antw OR/OF (3) 8  correct trig ratio/ sin 2x = korrekte trigvh 10  correct trig eq/ korrekte trigvgl ∴ 2x = 53,1301... (2x < 90°)  answer/antw ∴ x = 26,57° (3) [24] Copyright reserved 12
Mathematics P2/Wiskunde V2 DBE/Feb.–Mrt. 2015 NSC/NSS – Memorandum 9.3 P T 1 V 2 R 1 2 30° 3 4 50° 4 3 2 Q W 1 1 2 S Z 9.3.1 Equal chords subtend equal ∠s/Gelyke koorde onderspan gelyke ∠e R (1) 9.3.2 Ŵ4 = 30° (tan chord theorem/rkl-koordst)  answer/antw  reason/rede Ŵ1 = 30°  answer/antw (3) 9.3.3(a) R̂ 4 = Ŵ2 = 50° (tan chord theorem/rkl-koordst)  S R Ŝ 2 = R̂ 3 + Ŵ2 (ext∠ of ∆/buite ∠ v ∆) ∴ Ŝ 2 = 80° S (3) OR/OF R̂ 2 = R̂ 3 = 30° (= chords subtend =∠s /= kde onderspan=∠e)  S R R̂ 4 = Ŵ2 = 50° (tan chord theorem/rkl-koordst) ∴ Ŝ 2 = 80° S (3) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 13
Mathematics P2/Wiskunde V2 DBE/Feb.–Mrt. 2015 NSC/NSS – Memorandum 9.3.3(b) T̂2 = Ŝ 2 = 80° (ext ∠ of cyclic quad/buite∠ van koordevh)  SR V + Ŵ4 = T̂2 (ext∠ of ∆/buite∠ van ∆)  S ∴ V̂ = 50°  S (4) 9.3.4 In ∆RVW and/en ∆RWS:  using the correct ∆s/ gebruik korrekte ∆e R̂ 2 = R̂ 3 = 30° (proven/bewys in 9.3.1) S V̂ = Ŵ2 = 50° (proven/bewys in 9.3.3) S VŴR = Ŝ1 (3rd ∠ in ∆) R ∴∆RVW | | | ∆RWS (∠∠∠) (3rd ∠ in ∆) or (∠∠∠ ) WR RS ∴ = (∆RVW | | | ∆RWS) S RV WR ∴ WR 2 = RV . RS (5) [22] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 14
Mathematics P2/Wiskunde V2 DBE/Feb.–Mrt. 2015 NSC/NSS – Memorandum QUESTION/VRAAG 10 T N 1 1 R P M 10.1.1 corresponding ∠s/ooreenkomstige∠e; PN | | RT  answer/antw (1) 10.1.2 ∠; ∠; ∠ OR/OF ∠; ∠  answer/antw (1) 10.2 PM PN = ( ΔPNM | | | ΔRTM ) RM RT S PN =  S 3PN 1 = 3 (2) 10.3 PM 1 RP 2 = ∴ =  Use of Pyth. for RM 3 RM 3 RN2 and PN2 RN² – PN² = (RM² + NM²) – (PM² + NM²) (Pyth) 3  RM = RP = RM² – PM² 2 3  1 2  2 1 =  RP  −  RP   PM = RP 2 2  2  9 1 9 1  RP 2 & RP 2 = RP 2 − RP 2 4 4 4 4 (4) = 2RP² OR/OF Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 15
Mathematics P2/Wiskunde V2 DBE/Feb.–Mrt. 2015 NSC/NSS – Memorandum RN2 – PN2 = (RM2 + NM2) – (PM2 + NM2) (Pyth)  Use of Pyth. for = RM2 – PM2 RN2 and PN2 = (3PM)2 – PM2 RM = RP + PM = 8PM2  (3PM)2 – PM2 = 2(2PM)2  RP = 2PM = 2RP2 (4) OR/OF RN2 – PN2 = (RM2 + NM2) – (PM2 + NM2) (Pyth)  Use of Pyth. for = RM2 – PM2 RN2 and PN2 = (RP + PM)2 – PM2 RM = RP + PM = RP2 + 2RP.PM + PM2 – PM2  expansion/ 1 uitbreiding = RP2 + 2RP. RP 2 1 2  PM = RP = 2RP 2 (4) [8] Copyright reserved/Kopiereg voorbehou 16
Mathematics P2/Wiskunde V2 DBE/November 2014 NSC/NSS – Memorandum QUESTION/VRAAG 9 9.1 A k h D 1 E B C 9.1.1 Same base (DE) and same height (between parallel lines)  same base/dies Dieselfde basis (DE) en dieselfde hoogte (tussen ewewydige lyne) basis between | | lines/ tussen | | lyne (1) 9.1.2 AD S DB 1 AE × k  S 2 1 EC × k 2 But/Maar area ∆DEB = area ∆DEC S (Same base and same height/dieselfde basis en dieselfde hoogte) R area ∆ADE area ∆ADE ∴ = area ∆DEB area ∆DEC  S AD AE ∴ = (5) DB EC Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 17
Mathematics P2/Wiskunde V2 DBE/November 2014 NSC/NSS – Memorandum 9.2 A F D G E M B C 9.2.1 EM FD = (Line parallel one side of ∆ AM AD  S R OR prop th; EF | | BD) (Lyn ewewydig aan sy v ∆ EM 3 = OF eweredigst; EF ||BD)  answer/antw AM 7 (3) 9.2.2 CM = AM (diags of parm bisect/hoekl parm halv)  S R CM AM 7 = = (from 9.2.1/vanaf 9.2.1)  answer/antw ME ME 3 (3) 9.2.3 h of ∆FDC = h of ∆BDC (AD | | BC)  AD | | BC 1 FD.h area ∆FDC 2  subst into area = form/ subst in area ∆BDC 1 BC.h opp formule 2 FD = (opp sides of parm =) S AD (tos sye v parm =) 3  answer/antw = 7 (4) OR/OF area ∆FDC FD 3 = = (same heights)  S R area ∆ADC AD 7 (dieselfde hoogtes) But Area ∆ADC = Area ∆BDC (diags of parm bisect area) S (hoekl v parm halv opp) area ∆FDC 3  answer/antw = area ∆BDC 7 (4) [16] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 18
Mathematics P2/Wiskunde V2 DBE/November 2014 NSC/NSS – Memorandum QUESTION/VRAAG 10 P 1 2 S 1 2 1 2 T 3 4 X 1 W 2 1 x 2 Q y 3 4 3 2 R 1 Y 10.1.1 Tangent chord theorem/Raaklyn-koordstelling R (1) 10.1.2 Tangent chord theorem/Raaklyn-koordstelling R (1) 10.1.3 Corresponding angles equal/Ooreenkomstige ∠e gelyk R (1) 10.1.4 ∠s subtended by chord PQ OR ∠s in same segment R ∠e onderspan deur dieselfde koord OF ∠e in dieselfde segment (1) 10.1.5 alternate ∠s/verwisselende ∠e ; WT | | SP R (1) 10.2 RW RT = (Line parallel one side of ∆ OR SR RS RP prop th; WT | | SP) ∴ RT = WR.RP (Lyn ewewydig aan sy v ∆ OF (2) RS eweredighst: WT | | SP) OR/OF ∆RTW | | | ∆RPS (∠; ∠; ∠) S RW RT ∴ = (∆RTW | | | ∆RPS) S RS RP RW.RP ∴ RT = (2) RS 10.3 y = T̂2 = R̂ 3 (tan chord theorem/Rkl-koordst) SR y = R̂ 3 = Q̂1 (∠s in same segment/∠e in dieselfde SR segment) (4) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 19
Mathematics P2/Wiskunde V2 DBE/November 2014 NSC/NSS – Memorandum P 1 2 x S 1 y 2 1 y 2 T 4 X 1 x3 W 2 y 1 x 2 Q y y 3 4 3 2 R 1 Y 10.4 Q̂ 3 = PŜR (ext ∠ of cyc quad/buite∠ v kdvh) S R PŜR = Ŵ2 (corresp∠s/ooreenk ∠e ; WT | | SP) S ∴ Q̂ 3 = Ŵ2 (3) OR/OF Q̂ 2 = x (∠s in same segment/∠e in dies segment) R Q̂ 3 = 180° − ( x + y ) (∠s on straight line/∠e op reguitlyn) S Ŵ2 = 180° − ( x + y ) (∠s of ∆WRT/∠e v ∆WRT ) S (3) ∴ Q̂ 3 = Ŵ2 10.5 In ∆RTS and ∆RQP: R̂ 3 = R̂ 2 = y (proven above/hierbo bewys) S Ŝ 2 = P̂2 (∠s in same segment/∠e in dies segment)  S/R RT̂S = RQ̂P (3 angle of ∆) rd  S OR/OF ∴∆RTS | | | ∆RQP (∠; ∠; ∠) (∠; ∠; ∠) (3) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 20
Mathematics P2/Wiskunde V2 DBE/November 2014 NSC/NSS – Memorandum 10.6 RT RS  S = (∆RTS | | | ∆RQP) RQ RP RS RS RS RT RS × on both × = × RP RP RP RQ RP sides 2  RS   RT  RS    =    RP   RP  RQ   RT  RS   RW  RS      =   (proven in 10.2/bewys in 10.2)  RP  RQ   RS  RQ  (3) RW = RQ OR/OF RT RS = (∆RTS | | | ∆RQP) S RQ RP WR.RP WR.RP But RT = (proven in 10.2/bewys in 10.2)  RT = RS RS RT WR.RP RS ∴ = = RQ RQ.RS RP multiplication/ WR.RP 2 = RQ.RS 2 vermenigvuldig WR RS 2 ∴ = RQ RP 2 (3) OR/OF RT RQ S = (∆RTS | | | ∆RQP) RS RP RT.RP RQ = RS RT.RS RT.RS  WR = and WR = (proven in 10.2/bewys in 10.2) RP RP RT.RS WR = RP RQ RT.RP RS  simplification/ RT.RS RS = × vereenvoudiging RP RT.RP 2 RS = RP 2 (3) [20] Copyright reserved/Kopiereg voorbehou 21
Wiskunde/V2 DBE/2014 NSS – Graad 12 Model – Memorandum VRAAG 9 9.1 D̂ =  = x (rkl-koordstelling)   = x 4  rede  = D̂ = x (∠e tos gelyke sye)   = D̂ = x 2 2 (S/R) (3) 9.2 M̂1 = 2x (buite ∠v∆) OF (∠ by midpt = 2∠ by omtr)  M̂ = 2x (S/R) 1 MD̂E = 90° (radius ⊥ rkl)  MD̂E = 90° M̂ 2 = 90° − 2 x (S/R) ∴ Ê = 180° − (90° + 90° − 2 x) (som v ∠e in ∆MDE)  Ê = 2 x = 2x ∴ CM is ‘n rkl (omgek rkl-koordst)  rede (4) 9.3 M̂ = 90° (EM ⊥ AC)  M̂ 3 = 90° 3 AD̂B = 90° (∠ in halfsirkel)  AD̂B = 90° (S/R) ∴ FMBD is koordevh (buite∠ v vh = tos binne ∠)  rede OF (3) EM̂C = 90° (EM ⊥ AC)  EM̂C = 90° AD̂B = 90° (∠ in halfsirkel)  AD̂B = 90° (S/R) ∴ FMBD is koordevh (tos ∠e v vh suppl)  rede (3) 9.4 DC2 = MC2 – MD2 (Pythagoras)  Pythagoras = (3BC)2 – (2BC)2 (MB = MD = radii)  substitusie = 9BC2 – 4BC2  9BC2 – 4BC2 = 5BC2 (3) 9.5 In ∆DBC en ∆DFM: D̂ 4 = D̂ 2 = x (bewys in 9.1)  D̂ 4 = D̂ 2 B̂1 = F̂2 (buite ∠ v koordevh)  B̂ = F̂ 1 2  rede Ĉ = M̂ 2 ∴∆DBC | | | ∆DFM (∠; ∠; ∠)  Ĉ = M̂ 2 of (∠; ∠; ∠) (4) 9.6 DM DC = (∆DBC | | | ∆DFM) S FM BC 5BC = BC  antwoord = 5 (2) [19] Kopiereg voorbehou Blaai om asseblief 22
Wiskunde/V2 DBE/2014 NSS – Graad 12 Model – Memorandum VRAAG 10 10.1 A h k D E B C Konstruksie: Verbind DC en BE en trek hoogtes k en h  konstruksie 1 opp ΔADE AD opp ΔADE 2 .AD.k AD  = = = (gelyke hoogtes) opp ΔDEB DB opp ΔDEB 1 .DB.k DB 2  rede 1 .AE.h opp ΔADE AE opp ΔADE 2 AE  = = = (gelyke hoogtes) opp ΔDEC EC opp ΔDEC 1 .EC.h EC 2 Maar Opp ∆DEB = Opp ∆DEC (dies basis, dies hoogte)  Area ∆DEB = Area ∆DEC (S/R) opp ΔADE opp ΔADE  ∴ = opp ΔDEB opp ΔDEC opp ΔADE opp ΔADE = AD AE opp ΔDEB opp ΔDEC ∴ = DB EC (6) Kopiereg voorbehou Blaai om asseblief 23
Wiskunde/V2 DBE/2014 NSS – Graad 12 Model – Memorandum 10.2.1 AB AC AB AC = (Ewered st; BC | | ED)  = BE CD BE CD 1 3 (S/R) =  substitusie 3 CD ∴ CD = 9 eenhede  antwoord (3) 10.2.2 DG FD DG FD = (Ewered st; FG | | EA)  = (S/R) GA FE GA FE 9− x 3 =  substitusie 3+ x 6 54 – 6x = 9 + 3x  vereenvoudig –9x = –45 x=5  antwoord (4) 10.2.3 In ∆ABC en ∆AED: Â is gemeen  Â is gemeen AB̂C = Ê (ooreenk ∠s; BC | | ED)  AB̂C = Ê (S/R) AĈB = D̂ (ooreenk ∠s; BC | | ED)  AĈB = D̂ (S/R) ∆ABC | | | ∆AED (∠, ∠, ∠) of (∠; ∠; ∠) BC AC BC AC ∴ =  = ED AD ED AD BC 3 = 9 12 1 BC = 2 eenhede  antwoord 4 (5) 10.2.4 1  gebruik v opp opp ΔABC 2 AC.BC.sin AĈB = reël opp ΔGFD 1 GD.FD.sin D̂  korrekte sye en 2 1 1 ∠e (3)(2 ) sin D̂  substitusie v = 2 4 (ooreenk ∠s; BC | | ED) waardes 1 (4)(3) sin D̂  sin AĈB = sin D̂ 2 9 (S/R) =  antwoord 16 (5) [23] Kopiereg voorbehou 24
Mathematics P3/Wiskunde V3 DBE/November 2013 NSC/NSS – Memorandum QUESTION/VRAAG 9 A 2x B x C F E D 9.1 AF : FE =2:1 (Prop Th; FB || EC)  answer (Eweredigheid St; FB || EC)  reason (2) 9.2 AF 2 = FE 1 AF 8 FE = = = 4 cm  FE = 4 cm 2 2  AE = 12 cm AE = 12 cm ED 1 ED 1 = (BE || DC; Prop Th) / (BE || DC; Eweredigheid St)  = AE 2 AE 2 ED 1 = 12 2  answer ED = 6 cm (4) [6] Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 25
Mathematics P3/Wiskunde V3 DBE/November 2013 NSC/NSS – Memorandum QUESTION/VRAAG 12 K 1 2 3 x x 1 E 2 2 1 O3 4 x T 2 3 x 1 1 x 2 Y W 12.1 K̂ 3 = x (tan ch th)  K̂ 3 = x (raaklyn koord)  tan ch th Ŷ2 = x (∠s in same seg)  Ŷ2 = x (∠e in selfde seg)  ∠s in same seg K̂ 2 = x (∠s opp = radii) / (= chs subt = ∠s)  K̂ 2 = x (∠e oork = radiusse) / (= koorde = ∠e)  reason Ŵ2 = x (∠s in same seg) / (= chs subt = ∠s)  Ŵ2 = x (∠e in selfde seg) / (= koorde = ∠e)  reason (8) 12.2 Ô1 + Ô 4 = 180° − 2 x (sum of int ∠’s of ∆) / (opp∠ cyclic quad)  Ô1 + Ô 4 = 180° − 2 x (som van binne∠e ∆) / (oorst ∠ koordevierhoek)  reason T̂ = 90° − x (∠ at circ cent = 2∠ at circumference)  reason (3) Copyright reserved/Kopiereg voorbehou Please turn over/Blaai om asseblief 26
Mathematics P3/Wiskunde V3 DBE/November 2013 NSC/NSS – Memorandum 12.3 Ê 2 = 90° (sum of int ∠’s of ∆) / (som van binne∠e ∆)  Ê 2 = 90° KE = ET (⊥ from centre to chord bisects chord)  sum of int ∠’s of ∆ (⊥ van middelpunt tot koord halveer koord)  ⊥ from centre to chord bisects chord OR (3) K̂1 + K̂ 2 + K̂ 3 = 90° − x (sum of int ∠’s of ∆)  K̂1 + K̂ 2 + K̂ 3 = 90° − x In ∆KWE and ∆TEW  sum of int ∠’s of ∆ 1. K̂1 + K̂ 2 + K̂ 3 = T̂ = 90° − x (proven above) 2. Ŵ1 = Ŵ2 = x (Proven in 12.1) 3. WE is common ∴ ∆KWE ≡ ∆TEW (∠∠S)  ∆KWE ≡ ∆TEW KE = ET (3) 12.4 In ∆KOE and ∆WTE  ∆KOE and ∆WTE i. K̂ 3 = Ŵ2 = x (proven)  K̂ 3 = Ŵ2 = x ii. Ê 2 = Ê 1 = 90° (∠s on str line / sum of int ∠’s of ∆)  Ê 2 = Ê 1 = 90° (∠e op reguit lyn / som van binne∠e ∆) iii. Ô 2 = T̂ = 90° − x (3rd ∠ of ∆)  Ô 2 = T̂ = 90° − x ∆KOE ||| ∆WTE (∠∠∠) KE OE KE OE = (||| ∆s)  = WE TE WE TE KE = TE (proven) KE.TE = OE.WE  KE = TE KE 2 = OE.WE (6) OR  ∆KOE and ∆WTE In ∆KOE and ∆KWE  K̂ 3 = Ŵ1 = x i. K̂ 3 = Ŵ1 = x (proven)  Ê1 is common ii. Ê1 is common iii. Ô 2 = K̂1 + K̂ 2 + K̂ 3 (3rd ∠ of ∆)  ∠∠∠ ∆KOE ||| ∆WKE (∠∠∠) KE OE KE OE = (||| ∆s)  = WE KE WE KE KE 2 = OE.WE (6) [20] Copyright reserved/Kopiereg voorbehou 27
Mathematics/P3 DBE/November 2012 NSC – Memorandum QUESTION 7 F L P Q M N G H 7.1 Draw a point P on FG such that FP = LM and a point Q on FH  construction such that FQ = LN. Note: No construction In ∆FPQ and ∆LMN constitutes a breakdown, hence no marks All three statements 1. F̂ = L̂ (given) 2. FP = LM (construction) must be given 3. FQ = LN (construction) ∴∆FPQ ≡∆LMN (SAS) ∆FPQ ≡∆LMN (SAS) FP̂Q = LM̂N (≡∆s)  FP̂Q = LM̂N But FĜH = LM̂N (given) FP̂Q = FĜH  FP̂Q = FĜH PQ || GH (corresponding angles =) FP FQ  PQ || GH = (PQ || GH ; Prop Th) FP FQ FG FH  = FG FH LM LN = (7) FG FH Copyright reserved Please turn over 28
Mathematics/P3 DBE/November 2012 NSC – Memorandum V 2x – 10 4 2x – 10 T P 66 99 9 K R 7.2 VP VT VP VT = (PT || RK;Prop Th)  = PR TK PR TK 2 x − 10 4  (PT || RK; Prop Th) =  substitution 9 6 2 x − 10 = 6 2 x = 16 x=8  answer (4) OR VP VT VP VT = (PT || RK; Prop Th)  = VR VK VR VK 2 x − 10 4  (PT || RK; Prop Th) = 2 x − 1 10  substitution 20 x − 100 = 8 x − 4 12 x = 96  answer x=8 (4) [11] Copyright reserved Please turn over 29
Mathematics/P3 DBE/November 2012 NSC – Memorandum QUESTION 9 C x B 1 4x T 2 3 360° – 2x x 1 O 180° – x2 2x K 1 2 3 A 9.1 AÔB = 2 x (∠circ centre = 2 ∠ circumference)  AÔB = 2 x T̂ = 180° − 2 x (opp∠ cyclic quad suppl) ∠circ centre = 2 ∠ circumference opp∠ cyclic quad suppl (3) 9.2 CÂT = x (∠ sum ∆)  CÂT = x K̂ 1 = x (ext∠ cyclic quad) ∠ sum ∆ CÂT = K̂ 1  K̂1 = x BK || AC (corresponding ∠s =) ext∠ cyclic quad  corresponding ∠s = OR (5) K̂1 = Ĉ = x (ext∠ cyclic quad)  K̂1 = Ĉ = x B̂ 4 = x (∠ sum ∆) ext∠ cyclic quad  B̂ 4 = x B̂ 4 = Ĉ = x ∠ sum ∆ BK || CA (corresponding ∠s =)  corresponding ∠s = (5) OR  CÂT = x CÂT = x (∠ sum ∆) ∠ sum ∆ BK̂A = 180° − x (opp∠ cyclic quad)  BK̂A = 180° − x CÂT + BK̂A = 180° opp∠ cyclic quad BK || AC (coint∠s supp) co-int∠s supp (5) Copyright reserved Please turn over 30
Mathematics/P3 DBE/November 2012 NSC – Memorandum 9.3 In ∆BKT and ∆CAT 1. CÂT = K̂ 1 (= x)  CÂT = K̂ 1 2. T̂ is common  T̂ is common 3. AĈT = B̂4 (∠ sum ∆) ∆BKT ||| ∆CAT (∠∠∠) ∠∠∠ (3) 9.4 AC AT AC AT = (||| ∆s)  = KB KT KB KT AC 7  ||| ∆s =  answer KB 2 (3) [14] Copyright reserved Please turn over 31
Mathematics/P3 DBE/November 2011 NSC – Memorandum QUESTION 9 9. Ĉ = 90° (∠s in semi circle) 9 Ĉ = 90° OÊA = 90° (corres ∠s; OD || BC) 9 OÊA = 90° AE = 8 cm (line from circ cent ⊥ ch bis ch) B 9 line from circ OE = 6 cm (Pythagoras) cent ⊥ ch bis ch ED = 10 – 6 O 9 OE = 6 cm = 4 cm 9 ED = 4 cm A OR Ĉ = 90° (∠s in semi circle) E C OÊA = 90° (corres ∠s; OD || BC) 9 Ĉ = 90° 9 OÊA = 90° D OE || BC (given) OA = OB (radii) 9 midpoint AE = EC = 8cm (midpoint theorem) theorem OE = 6 cm (Pythagoras) 9 OE = 6 cm ED = 10 – 6 9 ED = 4 cm = 4 cm OR Ĉ = 90° (∠s in semi circle) BC2 = (20)2 – (16)2 9 Ĉ = 90° BC2 = 144 9 BC = 12 BC = 12 9 reason 1 9 OE = 6 cm OE = BC (midpoint theorem) 9 ED = 4 cm 2 OE = 6 cm OD = 10cm [5] ED = 10 – 6 = 4 cm OR Ĉ = 90° (∠s in semi circle) 9 Ĉ = 90° BC = (20) – (16)2 2 2 9 BC = 12 BC2 = 144 9 reason BC = 12 1 OE = BC (midpoint theorem) 9 OE = 6 cm 2 9 ED = 4 cm OE = 6 cm ED = 4cm [5] Copyright reserved Please turn over 32
Mathematics/P3 DBE/November 2011 NSC – Memorandum QUESTION 10 A x F B 1 3 2 3 H 2 1 G 3 1 2 1 y x x2 E 3 2 x 4 1y C D 10.1 Â = D̂ 4 = x (tan ch th) 9 Â = x Ê 2 = x (tan ch th) OR (∠s in same seg) 9 tan ch th 9 Ê 2 = x D̂ 2 = Â = x (alt ∠s; CA || DF) 9 reason 9 D̂ 2 = x 9 alt ∠s; CA || DF (6) 10.2 In ΔBHD and Δ FED 1. B̂ 2 = F̂ (∠s in same seg) 9 B̂ 2 = F̂ 2. D̂ 3 = D̂1 (= chs subt = ∠s) 9 ∠s in same seg 9 D̂ 3 = D̂1 ΔBHD ||| Δ FED (∠∠∠) 9 = chs subt = ∠s 9 ∠∠∠ (5) 10.3 FE FD FE FD = (||| Δs) 9 = BH BD BH BD But FE = AB (given) 9 FE = AB AB FD (2) = BH BD AB.BD = FD.BH [13] Copyright reserved Please turn over 33
Mathematics/P3 DBE/November 2011 NSC – Memorandum QUESTION 11 B A F E C D P Q 11.1 AF = FC (diags of parallelogram bisect) 9 AF = FC FE || CD AE = ED (Prop Th; FE || CD) OR (Midpoint Theorem) 9 reason (2) 11.2 AC 1 = (given) CP 2 AD 1 = (given) DQ 2 AC AD 9 ratios equal = CP DQ CD || PQ (converse proportionality theorem) 9 CD || PQ CD || FE (given) 9 reason: converse ∴ PQ || FE prop th and conclusion (3) OR AC 1 = AP 3 AD 1 = AQ 3 AC AD 9 ratios equal = AP AQ CD || PQ (converse proportionality theorem) 9 CD || PQ CD || FE (given) 9 reason: converse ∴ PQ || FE prop th and conclusion (3) OR AF 1 AF 1 = 9 = AP 6 AP 6 AE 1 = AQ 6 AF AE AF AE 9 = = AP AQ AP AQ 9 conv prop theorem ∴ PQ || FE (converse proportionality theorem) Copyright reserved Please turn over 34
Mathematics/P3 DBE/November 2010 NSC - Memorandum 8.2 C 2 D 1 4 B 3 1 2 1 2 O 1 3 2 F x A E 8.2.1 B̂ 4 = x (tan chord theorem) 9 B̂ 4 = x Note: 9 tan chord theorem If start with  = x and 9  = B̂4 = x with  = B̂4 = x (corres ∠; BD || AO) do not use tan ch th: reason max 2 marks B̂ 2 = x (BO = EO = radii) 9 B̂ 2 = x (4) 8.2.2 DB̂E = 90° (∠ in semi-circle) 9 DB̂E = 90° CB̂E = 90° + x 9 ∠ in semi-circle 9 CB̂E = 90° + x (3) OR CB̂O = 90° (rad ⊥ tan) 9 CB̂O = 90° CB̂E = 90° + x 9 rad ⊥ tan 9 CB̂E = 90° + x OR (3) Ô1 = 2 x (∠ circ cent) B̂3 = D̂1 = 90° − x (radii) 9 Ô1 = 2 x 9 ∠ circ cent CB̂E = x + (90° − x) + x 9 CB̂E = 90° + x = 90° + x (3) 8.2.3 DB̂E = 90° (proved in 8.2.2) 9 DB̂E = 90° BF̂O = 90° (co-int angles supp; BD || AO) 9 BF̂O = 90° and BF = FE (line from circ cent ⊥ ch bisect ch) reason F is the midpoint of EB 9 BF = FE 9 line from circ cent ⊥ ch bisect ch) (4) 35
Mathematics/P3 DBE/November 2010 NSC - Memorandum OR OD = OE (radii) 9 OD = OE BF = FE (BD || AO) 9 radii F is the midpoint of EB 9 BF = FE 9 BD || AO (4) OR BF̂O = EF̂O = 90° (BD || AO) 9 BF̂O = EF̂O = 90° OF is common (BD || AO) BO = OE (radii) 9 BO = OE ΔBOF ≡ ΔEOF (90°HS) 9 ΔBOF ≡ ΔEOF BF = FE (≡ Δs) 9 BF = FE (4) OR B̂2 = Â = x (proven) Ô 2 is common 9 ΔAOB ||| ΔBOF ΔAOB ||| ΔBOF (AAA) AB̂O = BF̂O 9 AB̂O = BF̂O AB̂O = 90° (proven) AB̂O = BF̂O = 90° 9 BF = FE BF = FE (line from circ cent ⊥ ch bisects ch) 9 line from circ cent ⊥ ch bisects ch (4) OR DB̂E = 90° (∠ in semi-circle) 9 DB̂E = 90° B̂3 = 90° − x 9 F̂1 = 90° 9 BF = FE Ô 2 = 90° − x (alt ∠s; BD || FO) 9 line from circ cent F̂1 = 90° (∠ sum Δ) ⊥ ch bisects ch BF = FE (line from circ cent ⊥ ch bisects ch) (4) OR In ΔOBF and ΔOEF 9 OB = OE 1. OB = OE (radii) 9 BF̂O = EF̂O = 90° 2. BF̂O = EF̂O = 90° (BD || AO) (BD || AO) 3. B̂2 = Ê (radii) 9 ΔOBF ≡ ΔOEF 9 BF = FE ΔOBF ≡ ΔOEF (AAS) (4) BF = FE 8.2.4 In ΔCBD and ΔCEB 9 Ê = B̂ 4 = x 1. Ê = B̂ 4 = x (proven in 8.2.1) 9 Ĉ is common 2. Ĉ is common Or 3. D̂ 4 = CB̂E = 90° + x 9 ΔCBD ||| ΔCEB (AAA) D̂ 4 = CB̂E = 90° + x Any two of the above (2) 36
Mathematics/P3 DBE/November 2010 NSC - Memorandum 8.2.5 EB CE EB CE = (sim Δs ∴ sides in proportion) 9 = BD CB BD CB EB.CB = CE.BD 9 EB.CB = CE.BD but EB = 2EF (F is the midpoint of BE) 9 EB = 2EF 2EF.CB = CE.BD (3) [21] QUESTION 9 9. Â = D̂ (∠ in same seg) 9 Â = D̂ S/R B̂ = Ĉ (∠ in same seg) 9 B̂ = Ĉ S/R AÊB = DÊC (vert opp ∠s) 9 AÊB = DÊC ΔDEC ||| ΔAEB (∠∠∠) D 999 ΔDEC ||| DE EC DC ΔAEB = = (sides in prop) AE EB AB (∠∠∠) x 8 Let AC = 11a A 4a x 7a = E 7a 4a 8 C [6] 28a 2 x= y 8 8 x = 3,5a 2 y 8 = (sides in prop) B 8 7a 64 y= 7a If candidate proves similarity of two triangles: full marks. If candidate does not prove similarity max 3 marks. The triangles have to be in the correct order in order to be given 3 marks. 37
Mathematics/P3 DBE/November 2010 NSC - Memorandum QUESTION 10 F E M A || || D B C 10.1 MÊC = 90° (tan ⊥ rad) 9 MÊC = 90° MD̂C = 90° (line from cent bisects ch) (tan ⊥ rad) MÊC + MD̂C = 180° 9 MD̂C = 90° ∴ MDCE a cyclic quad (opp ∠s of quad supplementary) 9 opp ∠s of quad NOTE: supplementary OR If the word (3) MÊC = 90° (tan ⊥ rad) cyclic is used in 9 MÊC = 90° MD̂A = 90° (line from cent bisects ch) the last reason: (tan ⊥ rad) MÊC = MD̂A max 2 / 3 marks 9 MD̂A = 90° ∴ MDCE a cyclic quad (ext ∠ quad = int opp) 9 ext ∠ quad = int opp (3) 10.2 MD2 = MB2 – DB2 (Pythagoras; Δ MBD) 9 MD = MB2 2 – DB2 MC2 = MD2 + DC2 (Pythagoras; Δ MDC) 9 Pythagoras = MB2 – DB2 + DC2 9 MC2 = MD2 + DC2 (3) 10.3 DB = 30 (given) MB = 40 (radii) 9 MB = ME MC = (40) + (50) − (30)2 2 2 2 9 DB = 30 = 3 200 9 MC2 = 3200 MC = 40 2 = 56,57 or MC = 40 2 MC2 = ME2 + CE2 (Pythagoras) or MC = 56,57 CE2 = 3 200 − 1 600 CE2 = 1 600 CE = 40 mm 9 answer (4) OR MC2 = CE2 + ME2 – 2CE.ME.cos MÊC 9 cosine rule 3200 = CE 2 + (40) 2 − 2CE.(40).cos 90° 9 ME = 40 = CE 2 + 1600 9 MC2 = 3200 CE 2 = 1600 9 answer CE = 40 (4) [10] 38
Mathematics/P3 DoE/November 2009 NSC – Memorandum • Consistent Accuracy will apply as a general rule. • If a candidate does a question twice and does not delete either, mark the FIRST attempt. • If a candidate does a question, crosses it out and does not re-do it, mark the deleted attempt. QUESTION 9 O B A M C 9.1 BĈA = 90° (∠’s in a semi-circle) 9 answer (1) 9.2.1 AC = 10 2 − 8 2 (Pythagoras) 9 diameter = 10 = 36 =6 9 AC AM = 3 (line from circle centre ⊥ chord bisects chord 9 AM (3) OR midpoint theorem) 9.2.2 OM = 5 2 − 32 (Pythagoras) 9 OM =4 (OR midpoint theorem) Area ΔAOM : Area ΔABC 9 substitution 1 1 = .4.3 : .8.6 2 2 = 6 : 24 9 answer =1:4 (3) [7] OR Area ΔAOM : Area ΔABC 1 1 = .AM.OM.sin OÂM : .AC.AB.sin BÂC 2 2 1 1 = .4.3 : .8.6 2 2 = 6 : 24 Copyright reserved Please turn over 39
Mathematics/P3 DoE/November 2009 NSC – Memorandum • Consistent Accuracy will apply as a general rule. • If a candidate does a question twice and does not delete either, mark the FIRST attempt. • If a candidate does a question, crosses it out and does not re-do it, mark the deleted attempt. QUESTION 10 A 2 2 4 G H 1 1 B F 2 E C 1,5 D 10.1.1 AH 2 9 statement = (GHB || FEC) 9 reason HE 1 AH = 2y HE = y AE 2 = (BE || CD) 9 ED = 1,5y ED 1 ED = 1,5 y AH 2 = If learner stops at 2 : 1,5 : ED 1,5 no penalty AH 4 9 answer = (4) ED 3 10.1.2 BE 4 9 answer = (ΔAEB ||| ΔADC) 9reason (2) CD 6 2 = 3 10.2 HE = 2 cm (given) AH = 4 cm 9 AH and ED ED = 3 cm AD.HE = (AH + HE + ED).HE 9AD = AH + = (4 + 2 + 3).(2) HE + ED = 18 (2) [8] Copyright reserved Please turn over 40
Mathematics/P3 DoE/November 2009 NSC – Memorandum • Consistent Accuracy will apply as a general rule. • If a candidate does a question twice and does not delete either, mark the FIRST attempt. • If a candidate does a question, crosses it out and does not re-do it, mark the deleted attempt. QUESTION 11 1 A E 2 2 1 3 4 2 3 1F 4 O• B 2 3 1 C 2 1 D 11.1 D̂1 = Â 4 (tan-chord theorem) 9 Statement 9 Reason = Ĉ 2 (alt ∠’s , BA || CE) 9 S/R (3) OR Ĉ 2 = D̂ 2 (∠'s in same seg) 9 Statement = Â1 (tan-chord theorem) 9 Reason 9 S/R = Ê 2 (alt ∠’s , BA || CE) = D̂1 (∠'s in same seg) (3) OR Â 3 + Â 4 = 90° (tan ⊥ rad) F̂1 = 90° (AB || EC; coint ∠s) In ΔAFC: Ĉ 2 = 90° − Â 3 (∠ sum Δ) Ĉ1 + Ĉ 2 = 90° (∠s in semi circle) In ΔADC: D̂1 = 90° − Â 3 (∠ sum Δ) D̂1 = Ĉ 2 Copyright reserved Please turn over 41
Mathematics/P3 DoE/November 2009 NSC – Memorandum • Consistent Accuracy will apply as a general rule. • If a candidate does a question twice and does not delete either, mark the FIRST attempt. • If a candidate does a question, crosses it out and does not re-do it, mark the deleted attempt. 11.2 In ΔACF and ΔADC 1. Â 3 is common 9 Â 3 is 2. Ĉ 2 = D̂1 (proved) common ΔACF ||| ΔADC (∠∠∠) 9 Ĉ 2 = D̂1 9 Reason OR (3) In ΔACF and ΔADC 1. Â 3 is common 2. Cˆ = Dˆ 2 1 (proved) 3. F̂1 = AĈD (remaining ∠s in triangles) ΔACF ||| ΔADC 11.3 AF AC = (sim Δ’s ∴ sides in proportion) 9 statement AC AD AC.AC AF = AD 1 9 Statement AC = AO = AD (2radius = diameter) 2 1 AD. 2 AD 1 9 Simplification AF = 2 AD AD 9 Substitution AF = 4 4AF = AD (4) OR ΔAOC is equilateral 9 S/R ∴ AÔC = Â 3 = 60° AF 1 9 Statement cos 60° = = AC 2 9 Simplification 1 1 AF = AC = AO 2 2 9 Substitution 1 1 AF = ( AD) (2radius = diameter) 2 2 1 AF = AD 4 (4) AD = 4AF [10] Copyright reserved Please turn over 42
Mathematics/P3 DoE/November 2008 NSC – Memorandum QUESTION 9 P Q 1 2 2 x 1 W 1 1 2 2 1 T 3 2 R angle in a S ∧ semi-circle (1) 9.1 R 1 = 90° …( angle in a semi-circle) ∧ ∧ P 2 = 90° − x 9.2 P 2 = 90° − x …( angle between radius and tangent) ∧ ∧ ∧ ∧ S = 90° − P2 S = 90° − P2 …( ext. angle of Triangle)(sum of angles of triangle) 90° -( 90° - x ) = x = 90° – ( 90° – x ) = x (3) ∧ ∧ ∴ P1 = S = x ∧ ∧ ∧ ∧ 9.3 W 2 = P1 = x …( angles in the same segment) Q W R = P1 = x ∧ ∧ ∧ Also S = x …( proved 9.2) QWR = S ∧ ∧ reason (3) W2 = S ∴ SRWT is a cyclic quad…(ext angle = int. opposite angle) ∧ ∧ 9.4 In ∆ QWR ; ∆ QST Q W R = QST ∧ ∧ ∧ W 2 = S ….( proved 9.3) R Q W is common ∧ Q1 is common ∧ ∧ AAA or ∠∠∠ or W R Q = T 2 ….(remaining angles) equiangular or 3rd angle ∆ QWR ||| ∆ QST (AAA) or (∠∠∠) or equiangular equal (3) Copyright reserved Please turn over 43
Mathematics/P3 DoE/November 2008 NSC – Memorandum TS QT TS QT 9.5.1 = ….. ∆ QWR ||| ∆ QST = RW QR RW QR TS 8 TS 8 ∴ = = 2 4 2 4 4TS = 16 TS = 4 cm (3) ∴ TS = 4 cm 9.5.2 SQ TS = SQ TS WQ RW = WQ RW 4×5 SQ = = 10 cm 2 10 cm ∴ SR = SQ − RQ = 6 cm 6 cm (3) [16] Copyright reserved Please turn over 44
Mathematics/P3 DoE/November 2008 NSC – Memorandum QUESTION 10 A T F C E D B 10.1 CE CT 1 answer (1) = = ED TA 2 CE 1 10.2 From 10.1 = use of ratio ED 2 But DC = 9 cm ∴ DE = 6 cm DE = 6 cm (2) = BD. ∴D is the midpoint of BE. 10.3 FD BD proportion = TE BE 2 6 = answer (2) TE 12 6 × TE = 24 TE = 4 cm ALTERNATIVE proportion D is the midpoint of BE. (from 10.2) Then F is the midpoint of BT. … (sides in proportion) answer (2) ∴ TE = 2FD (midpoint theorem) = 4 cm Copyright reserved 45

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