WAEC Mathematics Past Questions & Answers - Page 147

731.

If tan x = 1, evaluate sin x + cos x, leaving your answer in the surd form

A.

2\(\sqrt{2}\)

B.

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

C.

\(\sqrt{2}\)

D.

2

Correct answer is C

tan x = 1; x = tan-1(10 = 45o

sin x + cos x

= sin 45o + cos 45o

= \(\frac{\sqrt{2}}{2} + \frac{\sqrt{2}}{2}\)

= \(\frac{\sqrt{2} + \sqrt{2}}{2}\)

= \(\frac{2\sqrt{2}}{2}\)

= \(\sqrt{2}\)

732.

If xo is obtuse, which of the following is true?

A.

x . 90

B.

180 < x < 270

C.

x < 90

D.

90 < x < 180

Correct answer is D

obtuse angle \(\to\) 90o < x < 180o

733.

The angles of a quadrilateral are (x + 10)o, 2yo, 90o and (100 - y)o, Find y in terms of x

A.

y = 160 + x

B.

y = 100 + x

C.

y = 160 - x

D.

y = x - 100

Correct answer is C

Sum of the angles in a quadrilateral = 360o

(x + 10o) + 2y + 90o + 100 - y = 360o

x + y + 200 = 360o

y = 360 - 200 - x

y = 160 - x

734.

If the volume of a cube is 343cm3, find the length of its side

A.

3cm

B.

6cm

C.

7cm

D.

96cm

Correct answer is C

Volume of a cube = (side)3

= (side)3

(side)3 = 343

side = 3\(\sqrt{343}\)

side = 7cm

735.

PQR is a sector of a circle centre O, radius 4cm. If PQR = 30o, find, correct to 3 significant figures, the area of sector PQR. [Take \(\pi = \frac{22}{7}\)]

A.

4.19cm2

B.

8.38cm2

C.

10.5cm2

D.

20.9cm2

Correct answer is A

Given q2 = 25 - r2.....(1)

from pythagora's theorem

P2 = q2 + r2.......(2)

put (1) into (2)

p2 = 25 - p2 + x2

p2 = 25

p = \(\sqrt{25}\)

= 5