WAEC Mathematics Past Questions & Answers - Page 105

521.

The graph is that of y = 2x2 - 5x - 3. For what value of x will y be negative? For what value of x will y be negative?

A.

-\(\frac{1}{2} \leq x\) < 3

B.

-\(\frac{1}{2} < x \leq 3\)

C.

-\(\frac{1}{2} < x < 3\)

D.

-\(\frac{1}{2} \leq x \leq 3\)

Correct answer is C

2x2 - 5x - 3 = 0

2x2 - 6x + x - 3 = 0

2x(x - 3) + 1(x - 3) = 0

(2x + 1)(x - 3) = 0

2x + 1 = 0

2x = -1

x = -\(\frac{1}{2}\)

x - 3 = 0

-\(\frac{1}{2}\) < x < 3

522.

In the diagram, |SR| = |QR|. < SRP = 65o and < RPQ = 48o, find < PRQ

A.

65o

B.

45o

C.

25o

D.

19o

Correct answer is D

< RSQ = < RPQ = 48o (angle in the same segment)

< SQR < RSQ (Base angle of an isosceles \(\bigtriangleup\))

< SQR = 480

< QRS + < RSQ + < RSQ = 180o(sum of interior angles of a \(\bigtriangleup\))

i.e. < QRS + 48o + 48o = 180

< QRS = 180 - (48 + 48) = 180 - 96 = 84o

but < PRQ + < PRS = < QRS

< PRQ = < QRS - < PRS - 84 - 65

= 19o

523.

The diagram is a circle of radius |QR| = 4cm. \(\bar{R}\) is a tangent to the circle at R. If TPO = 120o, find |PQ|.

A.

2.32cm

B.

1.84cm

C.

0.62cm

D.

0.26cm

Correct answer is C

No explanation has been provided for this answer.

524.

The diagram is a circle with centre P. PRST are points on the circle. Find the value of < PRS

A.

144o

B.

72o

C.

40o

D.

36o

Correct answer is A

Reflex < POS = 2x (angle at centre is twice that at circumference)

reflex < POS + < POS = 350o(angles at a point)

i.e. 2x + 8x = 360o

10x = 360o

x = \(\frac{360}{10}\)

= 36o

< PRS = \(\frac{1}{2}\)

< POS(< at centre twice that circumference)

= \(\frac{1}{2}\) x 8x = 4x

4 x 36o

< PRS = 144

525.

In the diagram, MN//PO, < PMN = 112o, < PNO = 129oo and < MPN = yo. Find the value of y

A.

51o

B.

54o

C.

56o

D.

68o

Correct answer is B

In \(\bigtriangleup\) NPO + PNO + PNO + < NOP = 180o(sum of interior angles of a \(\bigtriangleup\) )

i.e. NPO + 129 + 37 = 180

< NOP = 180 - (129 + 37) = 14o

< MNP = < NOP = 14o (alt. < s)

In \(\bigtriangleup\) MPN

< PMN + < MNP + y = 180(sum of interior angles of a \(\bigtriangleup\))

i.e. 112 + 14 + y = 180o

y = 180 - (112 + 14) = 180 - 126 = 54o