WAEC Past Questions and Answers - Page 2276

11,376.

The length of a rectangle is 10 cm. If its perimeter is 28 cm, find the area

A.

30cm\(^2\)

B.

40cm\(^2\)

C.

60cm\(^2\)

D.

80cm\(^2\)

Correct answer is B

perimeter = 2( length + breadth) 

→ 28 = 2 (10+ b) 

14 - 10 = b

b = 4 

Area = length x breadth

10 x 4 → 40cm\(^2\)

11,377.

In the diagram, ∠ZWZY and WYX are right angles. Find the perimeter of WXYZ.

A.

30cm

B.

32cm

C.

35cm

D.

37cm

Correct answer is B

In ΔWYZ: 

hyp\(^2\) = adj\(^2\) + opp\(^2\)

hyp\(^2\) =3\(^2\) + 4\(^2\) → 9 + 16

hyp\(^2\) = 25

hyp = 5

In  ΔWXY:

hyp\(^2\) = adj\(^2\) + opp\(^2\)

hyp\(^2\) = 12\(^2\) + 5\(^2\) = 144 +25

hyp\(^2\) = 169

hyp = 13

the perimeter of WXYZ. = 3+4+12+13 → 32cm

11,379.

A cylinder, opened at one end, has a radius of 3.5cm and height 8cm. calculate the total surface area

A.

126.5cm\(^2\)

B.

165.0cm\(^2\)

C.

212.0cm\(^2\)

D.

214.5cm\(^2\)

Correct answer is D

The surface area of an open-top cylinder = πr(r + 2h),

where 'r' is the radius and 'h' is the height of the cylinder.

= \(\frac{22}{7}\) * 3.5 (3.5 + 2 * 8)

= 11 (3.5 + 16) → 11 (19.5)

= 214.5cm\(^2\)

11,380.

A ladder 6m long leans against a vertical wall at an angle 53º to the horizontal. How high up the wall does the ladder reach?

A.

3.611m

B.

4.521m

C.

4.792m

D.

3.962m

Correct answer is C

Sin θ = \(\frac{opp}{hyp}\) → \(\frac{x}{6}\)

cross multiply:

sin53º * 6 = x

0.7986 * 6

 4.792m