MATHEMATICS PAPER 2
GRADE 12
MEMORANDUM
NATIONAL SENIOR CERTIFICATE
NOVEMBER 2016
NOTE:
QUESTION 1
Distance from the store in km | 1 | 2 | 3 | 4 | 5 | 7 | 8 | 10 |
Average number of times shopped per week | 12 | 10 | 7 | 7 | 6 | 2 | 3 | 2 |
1.1 | Strong | 🗸 (1) |
1.2 | –0,95 (–0,9462..) | 🗸 (1) |
1.3 | a = 11,71 (11,7132…) b = –1,12 (–1,1176…) yˆ = -1,12x + 11,71 | 🗸 value of a 🗸 value of b 🗸 equation (3) |
1.4 | yˆ = -1,12(6) + 11,71 = 5 times | 🗸 substitition 🗸 answer (2) |
1.5 | On scatter plot | 🗸🗸 A line close to any 2 of the following points: (5 ; 6) or (10 ;½ ) or (6 ; 5) or (0 ; 11,7) (2) [9] |
QUESTION 2
2.1 | Positively skewed OR skewed to the right | 🗸 answer (1) | ||||
2.2 | Rangeg = 2,21 – 1,39 = 0,82 m | 🗸 subtract values 🗸answer (2) | ||||
2.3 | 🗸95 , 133, 156 🗸160 (2) | |||||
Intervals | Cumulative frequency | |||||
1,3 ≤ x < 1,5 | 24 | |||||
1,5 ≤x < 1,7 | 95 | |||||
1,7 ≤ x < 1,9 | 133 | |||||
1,9 ≤ x < 2,1 | 156 | |||||
2,1 ≤ x < 2,3 | 160 | |||||
2.4 | OGIVE | 🗸 upper limits 🗸 cum f 🗸 shape 🗸 grounded (4) | ||||
2.5 | method (using 80 to determine the height) 1,65 (accept any value between 1,6 and 1,69) | 🗸 method 🗸 answer (2) | ||||
2.6.1 | The mean would change by 0,1 m | 🗸 answer (1) | ||||
2.6.2 | No influence/change as there is no difference in variation of data. | 🗸 answer (1) [13] | ||||
QUESTION 3
3.1 | M = Midpt of AC [diags of rectangle bisect/] | 🗸 x-value of M 🗸 y-value of M (2) |
3.2 | m BC = 3 - 0 = 3 6 - p 6 - p OR mBC = 0 - 3 = - 3 p - 6 p - 6 | 🗸answer (1) 🗸answer (1) |
3.3 | mAD = mBC [AD | | BC] mBC = 2 3 = 2 6 - p 3 = 12 - 2 p p = 4½ OR y - y1 = 2(x - x1) C(6 ;3) y - 3 = 2(x - 6) ∴ y = 2x - 9 but y = 0 ∴ x = 4½ = p OR | 🗸 mBC = 2 🗸 equating 🗸answer (3) 🗸 mBC = 2 🗸 substituting (6 ; 3) 🗸answer (3) |
y = 2x + c 3 = 12 + c - 9 = c y = 2x - 9 0 = 2x - 9 x = 9 ∴ p = 9 2 2 | 🗸 mBC = 2
🗸 substituting 🗸answer (3) | |
3.4 | DB =AC [diag of rectangle = ] AC = √170 \ DB = 170 or 13,04 | 🗸 substitution 🗸 length of AC 🗸 AC = BD (3) |
3.5 | tan a = mBC = 2 ∴ a = 63,43° | 🗸 tan a = mBC 🗸 a = 63,43° (2) |
3.6 | In quadrilateral OFBG: OFˆB = 63,43° [vert opp ∠s] FOˆ G = GBˆ F = 90° ∴ OGˆ B = 360° -[90° + 90° + 63,43°] [sum ∠s quad = 360°] ∴ OGˆ B = 116,57° OR mAB = -½ 90° + OGˆ A = 153,43° ∴ OGˆ A = 63,43° OGˆ B = 180° – 63,43° = 116,57° OR FOˆG = GBˆ F = 90° ∴ GOFB is cyc quad OGˆ B = 180° – 63,43° [∠s of cyc quad = 180°] = 116,57° OR OFˆB = 63,43° XOˆ G = FBˆ G = 90° ∴OGBF is a cyclic quad ∴ OGˆ B = 180° - 63,43° OGˆ B = 116,57° | 🗸 size of OFˆB 🗸 S 🗸 answer (3) 🗸 m = - ½ 🗸 S 🗸 answer (3)
🗸 S 🗸 S 🗸 answer (3) 🗸 S 🗸 S 🗸 answer (3) |
3.7 | M is the centre [BD is diameter] | 🗸 M is centre
🗸 r = √170 2
🗸 equation (3) |
3.8 | CBˆ M = BAˆ M = 45° [diag of square bisect ∠s] ∴BC will be a tangent [converse tan chord th] OR
| 🗸S 🗸 R (2) 🗸S 🗸 R (2) [19] |
QUESTION 4
4.1 | ∠ in semi circle/ ∠ at centre = 2Ð on circle | 🗸 R (1) |
4.2 | mTS = 7 - 2 3 - 5 = - 5 2 | 🗸 substitution 🗸 mTS (2) |
4.3 | mTS x mRS = -1 [TS ⊥ SR] mRS = 2 5 y = 2 x + c 5 2 = 2 (5) + c 5 c = 0 y = 2 x 5 OR | 🗸 mRS
🗸substitution m and (5 ; 2)
🗸 equation (3) |
mTS ´ mRS = -1 [TS ⊥ SR] ∴ mRS = 2 5 y - y1 = 2 (x - x1) 5 y - 2 = 2 (x - 5) 5 y = 2 x 5 | 🗸 mRS
🗸substitution m and (5 ; 2) 🗸 equation (3) | |
4.4.1 | 🗸 r 🗸 answer (2) 🗸 substitution 🗸 answer (2) | |
4.4.2 | OR Answer only: full marks Answer only: only 1 coordinate correct (1 mark) | 🗸 M 🗸 x coordinate 🗸 y coordinate(3) M 🗸 x coordinate 🗸 y coordinate (3) |
mTM= 9 - 3 = - 1 6 ½ - 7 12 TM : 7 = - 1 (3) + c y = - 1 x + 29....(1) 12 12 4 SR : y = 2 x............. (2) 5 2 x = - 1 x + 29 5 12 4 29 x = 29 60 4 ∴ x = 15 ∴ y = 2 (15) = 6 5 | 🗸 Equating 🗸 x coordinate 🗸 y coordinate(3) | |
4.4.3 | ST = OR | 🗸 substitution 🗸 answer 🗸 ratio (3) 🗸 area 🗸 rule 🗸 ratio (3) |
4.4.4 | [R⊥tangent] OR OR OR | 🗸mTR =-½ 🗸mKTL = 12 🗸y=12x - 29 (3) 🗸mTR =-½ 🗸mKTL = 12 🗸substitution (3;7)&(a;b) (3) 🗸subst into Pyth 🗸multiplication 🗸simplification (3) |
4.4.5 |
OR OR | 🗸substitution into disctance formula 🗸substitution of b=12a-29 🗸standard form 🗸subst into formula or factorise 🗸values of a 🗸values of b (6) 🗸substitution into disctance formula 🗸substitution of b=12a-29 🗸(a-3)2 =1 🗸±1 🗸values of a 🗸values of b (6) 🗸substitution 🗸substitution of b=12a-29 🗸standard form 🗸factors 🗸values of a 🗸values of b (6) [23] |
QUESTION 5
5.1.1 | sin196° = - sin16° = - p | 🗸reduction 🗸answer (2) |
5.1.2 |
OR | 🗸statement 🗸answer (2) 🗸x in terms of p 🗸answer (2) |
5.2 | sin(A + B) = cos[90° - (A + B)] = cos[(90° - A) - B] = cos(90° - A)cosB + sin(90° - A)sinB = sin AcosB + cos AsinB | 🗸co-ratio 🗸correct form 🗸expansion (3) |
5.3 |
OR OR
|
🗸 √sin2 2A 🗸 cosA 🗸 - sinA 🗸 2sinAcosA 🗸 answer (5) 🗸 2 cos2A -1 🗸 cosA 🗸 - sinA 🗸identity 🗸 answer (5) 🗸1-2sin2A 🗸cosA 🗸- sinA 🗸 identity 🗸 answer (5) |
5.4.1 | 🗸 identity 🗸 value of cos2B 🗸 answer 🗸 = √cos 2B + 1 2 🗸 value of cos2B 🗸 answer (3) | |
5.4.2 |
OR OR | 🗸 sin2B = 1 5 🗸 answer (2) 🗸 y = 1 🗸 answer (2) 🗸 sin2B = 1 5 🗸 answer (2) |
5.43 |
OR | [21] |
QUESTION 6
6.1 | 🗸 x- intercepts/ 🗸 y- intercept/ 🗸 turning pts/ (3) | |
6.2 | f (x) - 3 = 2 sin 2x - 3 ∴ maximum value = 2 – 3 = –1 | 🗸 🗸 answer (2) |
6.3 | 2 sin 2x = - cos 2x tan 2x = - ½ ref∠ = 26,57° 2x = 153,43° + k.180°; k ∈ Z x = 76,72° + k.90°; k ∈ Z or x = -13.28° + k.90°, k ∈ Z OR 2 sin 2x = - cos 2x tan 2x = - ½ ref ∠= 26,57° 2x = 153,43° + k.360° or 333,43° + k.360°, k ∈ Z x = 76,72° + k.180° or 166,72° + k.180° ; k ∈ Z | 🗸 tan 2x = - ½
or – 26,56o 🗸 76,72° or -13,28o 🗸 k.90°; k ∈ Z (4) 🗸 tan 2x = - ½ 🗸 2x = 153,43° &333,43° 🗸 76,72° &166,72o 🗸 k.180°; k ∈ Z (4) |
6.4 | x ∈ (-103,28°; - 13,28°) OR –103,28° < x < –13,28° | 🗸🗸 values 🗸notation(3) 🗸🗸 values 🗸notation (3) [12] |
QUESTION 7
7.1 | 🗸 substitution into Pyth 🗸 value of DB 🗸 answer (3) 🗸 correct ratio 🗸 OB as subject 🗸 answer (3) 🗸 correct ratio 🗸 special angle 🗸 answer (3) |
OR AOB = 90º (diagonals bisect ⊥) OB=OA AB2 = AO2 + BO2 [pyth] ∴AB2 = 2OB2 2OB2=32 | 🗸 OB = OA 🗸 Pyth 🗸 answer (3) | |
7.2 |
OR
| 🗸 substitution into Pyth 🗸 length of BE 🗸correct cosine rule 🗸 cos θ as subject 🗸 simplification (5) 🗸 substitution into Pyth 🗸 length of BE 🗸correct cosine rule 🗸 substituting 🗸 cos θ as subject (5) 🗸 substitution into Pyth 🗸 length of BE 🗸sketch with values 🗸 3/2 🗸substitution (5) 🗸E = 180º - 2θ 🗸sinE = sin2θ 🗸subst into sine rule 🗸diagram 🗸2sinθcosθ (5) |
7.3 | 🗸 substitution 🗸 x-value 🗸 substitution 🗸 answer (4) [12] |
QUESTION 8
8.1.1 | Alternate angles PQ || SR | 🗸 R (1) |
8.1.2(a) | Tˆ2 = 70° [∠s opp = sides] ∴Qˆ1 = 180° - 2(70°) [∠s/e Δ = 180°] = 40° | 🗸 S 🗸R 🗸 answer (3) |
8.1.2(b) | Pˆ1 = 40° [tangent chord th] | 🗸 S 🗸R (2) |
8.2
8.2.1 | AT = 20 [line from centre ⊥ to chord] | 🗸S(1) |
8.2.2 | OR Let OS = 7, then OT = 15 In ΔAOT: AO2 = 202 + 152 = 625 AO = 25 In ΔAOS: AO2 = 242 + 72 = 625 AO = 25 ∴ OA = 25 OR AO2 = OS2 + AS2 [Pyth : ΔAOS] OT 2 + AT2 = OS2 + AS2 [Pyth : ΔAOT] Let OT = 15x. Then OS = 7x But AS = 24 [line from centre ^ to chord] (15x)2 + 400 = (7x)2 + 576 225x2 + 400 = 49x2 + 576 176x2 = 176 x = 1 ∴AO =√225 + 400 = 25 | 🗸 equating 🗸 AS = 24 🗸 substitution OS = 7/15OT 🗸 OT 🗸 radius (5) 🗸🗸 testing in ΔAOT 🗸🗸 testing in ΔAOS 🗸conclusion (5) 🗸equating 🗸AS=24 🗸substitution 🗸x=1 🗸radius (5) 🗸AS=24 🗸substitution OS=7/15OT 🗸equating 🗸subst pyth 🗸radius (5) [12] |
QUESTION 9
9.1.1 | tangent chord theorem | 🗸 R (1) |
9.1.2 | corresponding ∠s/e; FB || DC | 🗸 R (1) |
9.2 | Eˆ1 = BCˆ D ∴ BCDE = cyclic quad [converse ext ∠ cyc quad] | 🗸 S 🗸 R (2) |
9.3 | Dˆ2 = Eˆ2 [∠s in the same segment] Dˆ2 = FBˆ D [alt ∠s, BF ||CD||CD] | 🗸 S 🗸 S (2) |
9.4 | Bˆ 3 = y OR Bˆ3 = Cˆ2 [∠s in the same segment] Bˆ2 = x - y OR Bˆ3 + Bˆ2 = x [from 9.3 and 9.4] Cˆ1 = x - y [from 9.2 and 9.3] ∴Bˆ 2 = Cˆ1 OR In Δ BFE and D BEC Eˆ1 = Eˆ2 [= x] Fˆ = Bˆ3 + Bˆ4 [tan - chord theorem] ∴ΔDBFE///DCBE [∠,∠,∠] ∴Bˆ 2 = Cˆ1 | 🗸 S 🗸 S 🗸 S (3) 🗸 identifying Δ ’s 🗸 S 🗸 S (3) [9] |
QUESTION 10
10.1
10.1 | Constr : Join S to R and T to Q and draw h1 from S ⊥ PT and h2 from T ⊥ PS | 🗸 constr (6) |
Proof :
|
10.2
10.2.1 | Corresponding ∠s/e; GF || LK | 🗸 R (1) |
10.2.2(a) | GL = FK OR GL = 2x [prop theorem; GF | | LK] LM KM y x 2GH = 2x [LH = HG] y x ∴GH = y | 🗸S 🗸 R 🗸 GL = 2GH (3) |
10.2.2(b) | K1 = GFM [corresponding∠s; GF || LK] LKM or → K1 = MHˆ F [ext ∠cyclic quad] MHˆF = GFM In ΔMFH and ΔMGF: Mˆ = Mˆ [common] MHˆF = GFˆM [proven] ∴ΔMFH | | | ΔMGF [∠∠∠] OR K1 = GFˆM [corresponding∠s; GF || LK] LKˆM or K1 = MHˆF [ext ∠cyclic quad] MHˆF = GFˆM In ΔMFH and ΔMGF: Mˆ = Mˆ [common] MHˆF = GFˆM [proven] Fˆ2 = Gˆ [∠s of Δ = 180°] ∴ΔMFH | | | ΔMGF | 🗸S 🗸 R 🗸 S 🗸 S 🗸 R (5) 🗸S 🗸 R 🗸 S 🗸 S 🗸 S (5) |
10.2.2(c) | ∴GF = MF [ ||| Δs] FH MH = 3x 2y | 🗸S 🗸R (2) |
10.2.3 | MF = MG [ ||| Δs] MH MF 3x = 3y [from 10.2.2(c)] 2y 3x
| 🗸 S 🗸substitution 🗸 simplificatio n (3) [20] |
TOTAL MARKS | 150 |