GRADE 12 MATHEMATICS
PAPER 2 
NSC PAST PAPERS AND MEMOS
SEPTEMBER 2017

MEMORANDUM

 QUESTIONS 1   

Employee   5  7 8 9 10
Hours in training        16  36  20  38  40  30  35 22 40 24
Productivity (units produced per day)   45  70  44 56   60  48  75 60 63 38
 1.1  SCATTER PLOT

✔2-4 correct points

✔5-7 correct points 

✔plotting all points

(3) 
1.2 a = 29,22
b = 0,89
y = 29,22 + 0,89x
✔ A
✔ B 
✔ equation
(3)
1.3 (30,9 ;55,50)
y-int 29, 22
✔ mean point (30,90;55,50 ) and y-int 29, 22
✔ regression line
(2)
1.4

y = 29,22 + 0,89(25)
= 51,47
OR
y = 51,38       [calculator use]
ANSWER ONLY FULL MARKS

✔ answer (2)
1.5 r = 0,66 ✔ answer (1)
1.6 Moderately strong positive correlation  ✔ answer (1) 
      [12]
QUESTION 2
2.1 140 learners ✔ answer (1)
2.2 60 < x £ 70 ✔ answer (1)
2.3 CUMMULATIVE GRAH ✔ grounding
✔ cummulative frequency
✔ plotting against the upper limit
✔ shape
(4)
2.3  Q3 - Q1  = 72 - 55
= 17
✔ Q3 & Q1
✔IQR
(2)
      [8]
QUESTION 3
 Q3RR
3.1  BC : x + 2 y = 14

y = - 1 x + 7
        2
mBC = mAD  = - 1/2
y - 5 = - 1 (x + 1)
             2
y = - 1 x + 9
        2       2

✔  = mAD  = - 1/2
✔ subst. m and A into correct formula
✔ y = - 1 x + 9
            2       2
(3) 
3.2

- 1 x + 9 = 0
  2       2
x = 9
D(9; 0)

OR

mAD   = mBC
0 - 5 = - 1
x + 1      2
- 10 = -x - 1
x = 9
D(9; 0)

✔ y = 0
✔ x = 9
✔ y = 0
✔x = 9
(2)
 3.3

mFD2 - 0
         10 - 9
= 2
mBC  × mFD  = 2 × - 1
                                 2
= -1
FD ⊥ BC     [mBC × mFD   = -1]

✔ correct subst.
✔  mFD = 2
✔ mBC × mFD   = -1
 (3)
3.4

AD =√(-1 - 9)2  + (5 - 0)2
= √125
= 5√ 5

✔ subt. into correct formula
✔  AD = 5√ 5

(2)
3.5

FD = √(9 -10)2  + (0 - 2)2
=  √5
A of ABCD = b ×  h
= 5 √5 ×√5
= 25

✔ subst. into correct formula
✔  FD = √5
✔  subst into correct formula
✔  answer

(4)
3.6

mAB  = mDC
 6 - 5    
   2 - (-1)
1
   3
∴ Inclination of DC = 18, 43º
Inclination of AD = 180º - tan-1 [½]
= 153, 43º
ADC = 153, 43º -18, 43º
= 135º
∴ ABC = 135º   [opp∠s of a parm.]

✔ subst. into correct formula
✔ mAB  = 1
                3
✔  θDC = 18, 43º
✔  θAC = 153, 43º
✔ AD C = 135º 
✔  ABC = 135º 

(6)
      [20]
QUESTION 4
q4
4.1

xS  = 0 + 4               yS   = 0 - 6
            2                               2
= 2                                   = -3
S(2; - 3)
Answer only full marks

✔ subst. into correct formula
✔  both coordinates

 
4.2

SP = √(2 - 4)2  + (- 3 + 6)2
= √13

✔ subst. into correct formula
✔  answer

(2)
4.3 (x - 2)2  + (y + 3)2   = 13

✔ correct subt. centre
✔  r 2 = 13.

(2)
4.4 Tangent ⊥ radius ✔ answer (1)
4.5

mrad  = - 3 + 6
              2 - 4
= - 3
     2
mtan = 2           [radius ⊥ tan] 
           3
y + 6 = 2 (x - 4)
            3
2 x - 26
   3       3

✔ subst. into correct form.
✔ mrad  = - 3
                   2
✔ mtan = 2         
                3
✔ subst. into correct form

(4)
4.6

(0 - 2) + (y + 3)2   = 13
(y + 3)2   = 9
y + 3 = ±3
yT = -6
T (0; - 6)

OR 

(0 - 2)2  + (y + 3)2   = 13
y 2 + 6 y = 0
y(y + 6) = 0
yT = -6
T (0; - 6)

OR 

Draw horizontal line y = -3 with M on OT
OM = MT         [⊥ from centre bisect the chord]

OM = 3
∴ MT = 3
∴ OT = 6
∴ T (0; - 6)

✔ x = 0
✔ (y + 3)2   = 9
✔ y + 3 = ±3
✔ yT = -6
✔ subs.x = 0 in eqn of circle
✔ standard form
✔ factors
✔ yT = -6
✔ S/R
✔ length of MT
✔ length of OT
✔ answer

(4)
4.7

At U , y = - 26
                   3
∴TU = 26 - 6
           3
8
   3
Area ΔOTP = 1/2 × 6 × 4
Area ΔPTU   1/2 × 8/3 × 4
9
   4

✔ U [ 0 ; -26/3]
✔ lenght of TU
✔ lenght of OT
✔ correct subst.
✔ answer
(5)
      [20]
QUESTION 5
5.1.1

sin 2x = √15
                8 
DIAGRAM ANS
cos2x = 2 cos2 x - 1
2 cos2 x = cos2x + 1
cos x = √cos2x + 1
                      2
= √ 7/8  + 1 
         2
= √15  
      4
 OR

cos2x = 2 cos2 x -1
7 = 2 cos2 x -1
8
15 = cos2 x
16
∴ cos x = √15  
                   4

✔ diagram 
✔  identity of cos2x 
✔  cos x subject of formula 
✔ cos2x = 7
                 8
✔  answer
✔  identity 
✔  cos2x = 7
                  8
✔ cos2 x = 15
                  16
✔ answer

(5)
5.2

sin(180º - θ ).sin(540º - θ ).cos(θ - 90º)
            tan(- θ ).sin2 (360º - θ )      
(sinθ)(sinθ ).(sinθ ).
   (- tanθ )(- sinθ )2
       sinθ      
        - sinθ
         cosθ
= -cosθ

✔ sin θ
✔  sin θ
✔  sin θ
✔  (- tanθ )
✔  (- sinθ )2
✔  sinθ = tan θ
     cosθ
✔  (- cosθ )

(7)
5.3.1

LHS = sin 5x. cos3x - cos5x.sin 3x -1
                          tan 2x
sin(5x - 3x) -1
        tan 2x
=        sin 2x          -1
          sin 2x
         cos 2x
= cos 2x -1
= 1- 2 sin 2 x -1
= -2 sin 2 x
∴ LHS = RHS

✔ sin (5x - 3x)
✔ tan 2x =  sin 2x
                  cos 2x

✔ simplification
✔ identity  
      1- 2 sin 2 x

(4)
5.3.2

tan 2x = 0
2x = 0º  or 180º
x = 0º  or 90º

OR

tan 2x is undefined
2x = 90º or 270º
x = 45º or 135º

✔ tan 2x = 0 / undefined
✔ 0º  or 180º
✔ 90º or 270º
✔ answer
(4)
      [20]
  QUESTION 6    
6.1 ANS 6.1 P2

f
🗸 both intercepts 
🗸asymptote
🗸shape  

g
🗸intercepts
🗸min& max values 
🗸shape

(6)
6.2 period(e) of f(½x) =  180º
                                   ½
= 360º
Answer only full marks
🗸 =  180º
         ½
🗸 360º
(2)
6.3 0º < x < 30º

🗸critical values 
🗸notation

(2)
6.4 x = 170º 🗸 answer (1)
      [11]
QUESTION 7
 q7
7.1 Area ΔABC = .AB.BC.sinB
                      2
= 1 × 17 × 17 × sin105º
   2
= 139,58

🗸 Area rule formula 
🗸 correct subst. 
🗸answer

(3)
7.2

AC 2 = AB2 + BC2 - 2.AB.BC.cosB
= 172 + 172 - 2.17.17.cos105º

= 727,5974081
∴AC = 26,97

🗸 cosine rule formula
🗸 correct subst into cosine rule
🗸 AC = 26,97

(3)
7.3

sinACDsinD
    AD         AC
sinACDsin75º
  13          26,97
sinACD = 13 × sin75º
                         26,97
= 0,4655927231
ACD = 27,75º

🗸 sine rule formula
🗸 correct subst. into sine rule
🗸 answer 

(3)
7.4

Converse opp ∠ s of a cyclic quad

OR

int.opp.∠ s of a quad suppl

 

🗸 reason

OR

🗸 reason

 (1)
      [10]
QUESTION 8
q8
8.1.1 S = 90º    [∠ in semi - circle] 🗸      S     
🗸      R
(2)
8.1.2 

T2   = S = 90º       [corresp.∠ s  RS ΙΙ Q]
∴ T is the midpt of SP         [ line from centre ⊥ to chord]
QP = 10 andTP = 8
QT2 = (10)2  -  (8)2                     [Pyth.Theorem]
∴ QT = 6
QU = QP = 10                [radii]
∴ TU = 4

🗸      S/R
🗸      S/R
🗸      subst. into Pyth. 
🗸       QT
🗸       S/R
🗸      TU

(6)
q8.2
8.2.1 B = 30º     [tan chord theorem] 🗸S         🗸 R (2)
8.2.2  P2 = 30º [alt ∠ s, BS ΙΙ PQ] 🗸S         🗸 R (2)
8.2.3  R = 150º  [opp  ∠ s of a cyclic quad] 🗸S         🗸 R (2)
8.2.4

Q2  = S3        [∠  s opp =sides] 
Q2 180º -150º                  [sum of ∠ sin a Δ] 
                  2
= 15º

🗸 S/R
🗸 S
🗸 answer

(3)
      [17]
QUESTION 9
q9.1
9.1

O1  = P1 + A and  O2 = P2 + B  [ext ∠ of a Δ] 
AO = OP = OB                           [radii] 
P1  = A  and  P2   = B                 [∠ s opp =sides] 
∴ O1  = 2P and O2   = 2P2
∴O1  + O = 2P1  + 2P2
AOB = 2 (P1 + P2)
= 2APB

🗸S/R
🗸S/R
🗸S/R
🗸S
(4)
q9.2
9.2.1

RUT = 90º        [∠ in a semi - circle] 
X1   = 90º       [line from centre to midpoint] 
∴RU ΙΙ SY [corresp.∠ s =] 

OR

RUT = 90º        [∠ in a semi - circle] 
X1   = 90º       [line from centre to midpoint]
∴ RUT + X2 = 90º + 90º = 180º
∴RU ΙΙ SY [co-int.∠ s supp] 

🗸S         🗸 R
🗸S         🗸 R
🗸 R
🗸S        
🗸 R
🗸S        
🗸 R
🗸 R

(5)
9.2.2

R2  = y                 [tan chord theorem] 
= O1                      [alt ∠s, RU ΙΙ SY]
∴T1 O1     [∠ at centre = twice ∠at circumf.]
          2     
= 1 y
   2

🗸S         🗸 R
🗸S         🗸 R
🗸 R
(5)
9.2.3

O = y = O1        [vert opp.∠ s] 
TUV = y            [tan from same point =in length] 
∴ TOUVis a cyclicquad            [converse same segment]

OR 

VTO = 90º                      [tan ⊥ radius] 

VUO = 90º                      [tan ⊥ radius] 

∴VTO + VUˆ O = 180º

∴TOUVisa cyclicquad   [converseoppÐsof cyclicquad.supp]

🗸S         🗸 R
🗸S         🗸 R
🗸 R
🗸S         🗸 R
🗸S         🗸 R
🗸 R

(5)
      [19]
QUESTION 10
q10
10.1

BA = BC    [prop theorem; EF ΙΙ  AC]
EA    FC
= CA   [prop theorem; ED ΙΙ BC]   
   DA
BCCA
  FC    DA

🗸S 🗸R
🗸S
🗸R
(4)
10.2 B2 = E3     [corresp ∠s : EDΙΙBC]
E1 = A        [corresp ∠s : EFΙΙAC]
∴F3 = D1     [sum of  ∠s of Δ ]
∴ΔBFE ΙΙΙ ΔEDA     [∠∠∠]
🗸S/R
🗸S/R
🗸R
(3)
10.3.1 AD = ED           [ΔBFE ΙΙΙ ΔEDA]
FE    BF
AD = 10 
 2      3,5 
AD = 40 = 5,71 
         7
🗸S
🗸R
🗸 subst.
🗸 AD
(4)
10.3.2 DC = EF = 2 [opp.sidesof a parm] 🗸S
🗸R
(2)
      [13]
      TOTAL : 150
Last modified on Tuesday, 13 July 2021 08:33