WAEC Mathematics Past Questions & Answers - Page 142

706.

Every staff in an office owns either a Mercedes and/or a Toyota car. 20 own Mercedes, 15 own Toyota and 5 own both. How many staff are there in the office?

A.

25

B.

30

C.

35

D.

45

Correct answer is B

M = Mercedez; T = Toyota

Number of staff = 0 + (20 - 5) + (15 - 5) + 5

0 + 15 + 10 + 5 = 30

707.

In the diagram, find the size of the angle marked a°

A.

60o

B.

80o

C.

120o

D.

160o

Correct answer is B

2 x s = 280°(Angle at centre = 2 x < at circum)

S = \(\frac{280^o}{2}\)

= 140°

< O = 360 - 280 = 80°

60 + 80 + 140 + a = 360°

(< in a quad); 280 + a = 360

a = 360 - 280

a = 80°

708.

In the diagram, < QPR = 60o

< PQR = 50o

< QRS = 2xo

< SRP = 3xo

< UQP = yo and RS//TU

calculate y

A.

102o

B.

78o

C.

70o

D.

60o

Correct answer is A

< RQT = < QRS = 2x (Alternate angles). But in \(\bigtriangleup\) PRQ

50 + 60 + (2x + 3x) = 180o(Angles in a triangle)

110 + 5x = 180o

5x = 180o - 110 = 70o

x = \(\frac{70}{5}\) = 14o

Also y + 50 + 2(14) = 180o

y + 50 + 28 = 180o

y = 180 - 78

y = 102o

709.

In the diagram, PX is a tangent to the circle and RST is an equilateral triangle. Calculate < PTS

A.

60o

B.

90o

C.

120o

D.

150o

Correct answer is C

\(\bigtriangleup\) RST is equilateral triangle, hence

< TRS = < RTS = < RSt = 60o

But < PTR = 60o(Angle between a chord and a tangent at the point of contact = Angle in the alt. segment). From the diagram < PTS = < PTR + < RTS

= 60o + 60o = 120o

710.

If the perimeter of \(\bigtriangleup\)PQR in thr diagram is 24cm, what is the area of \(\bigtriangleup\)PRS?

A.

19.5cm2

B.

15.0cm2

C.

13.0cm2

D.

9.3cm2

Correct answer is B

Perimeter of \(\bigtriangleup\) PQR = PQ + QR + PR

24cm = 6cm + 8cm = PR

24 = 14 + PR

PR = 24 - 14 = 10cm

Area of \(\bigtriangleup\) PRS = \(\frac{1}{2} \times 10 \times 3cm^3\)

= 15cm3