WAEC Mathematics Past Questions & Answers - Page 116

576.

Find the size of the angle marked x in the diagram.

A.

108o

B.

112o

C.

128o

D.

142o

Correct answer is C

x + 52o = 90

x = 90 - 52

x = 38o

k = opposite angle Z

k = 38o

y + k = 90o

y + 38o = 90o

y = 90o - 38o

y = 52o

y = x = 180o(sum of angles on straight line)

52 + x = 180o

x = 180 - 52

x = 128

577.

In the diagram, PO and OR are radii, |PQ| = |QR| and reflex < PQR is 240o. Calculate the value x

A.

60o

B.

55o

C.

50o

D.

45o

Correct answer is A

< Q = \(\frac{240}{2}\) (angle at centre twice that at the circumference)

< Q = 120o

Also < POR = 360 - 240

= 120o

( < s at centre) since /PQ/ = /QR/, < x = < R

Byt < x + < R + O + Q = 360 (sum of interior < s of quadrilateral)

x + R + 120 = 360o

x + R = 360 - 240 = 120; Since x = R

x + x = 120

2x = 120

Since x = R

x + x = 120

2x = 120

x = \(\frac{120}{2}\)

= 60o

578.

The diagram shows a cyclic quadrilateral PQRS with its diagonals intersecting at K. Which of the following triangles is similar to triangle QKR?

A.

\(\bigtriangleup\) PQK

B.

\(\bigtriangleup\) PKS

C.

\(\bigtriangleup\) SKR

D.

\(\bigtriangleup\) PSR

Correct answer is C

No explanation has been provided for this answer.

580.

If 27x = 9y. Find the value of \(\frac{x}{y}\)

A.

\(\frac{1}{3}\)

B.

\(\frac{2}{3}\)

C.

1\(\frac{1}{2}\)

D.

3

Correct answer is B

27x = 9y

33x = 32y

3x = 2y