WAEC Mathematics Past Questions & Answers - Page 307

1,531.

Find the area of an equivalent triangle of side 16cm

A.

64√3cm2

B.

72√3cm2

C.

96cm2

D.

128√3cm2

E.

128cm2

Correct answer is A

Area = 1/2 x 16 x 16sin60o = 64√3cm2

1,532.

In the diagram above, O is the center of the circle, |SQ| = |QR| and ∠PQR = 68°. Calculate ∠PRS

A.

34o

B.

45o

C.

56o

D.

62o

E.

68o

Correct answer is A

From the figure, < PQR = 68°

\(\therefore\) < QRS = < QSR = \(\frac{180 - 68}{2}\) (base angles of an isos. triangle)

= 56°

\(\therefore\) < PRS = 90° - 56° = 34° (angles in a semi-circle)

1,533.

In a given regular polygon, the ratio of the exterior angle to the interior angles is 1:3. How many side has the polygon?

A.

40

B.

5

C.

6

D.

8

E.

12

Correct answer is D

Let x be the exterior angle; interior = 3x; but x + 3x = 180o

4x = 180o; x = 45

= \(\frac{360}{45}\) = 8

1,534.

In the diagram above, ∠PTQ = ∠URP = 25° and XPU = 4URP. Calculate ∠USQ.

A.

100o

B.

120o

C.

125o

D.

130o

E.

150o

Correct answer is D

Since < URP = 25°, then < XPU = 4 x 25° = 100°

\(\therefore\) < TPQ = 180° - 100° = 80°

\(\therefore\) < PQT = 180° - (80° + 25°) = 75°

< SQR = 75° - 25° = 50° (exterior angle = 2 opp interior angles)

\(\therefore\) < USQ = 180° - 50° = 130°

 

1,535.

The angles of a pentagon are x°, 2x°, (x + 60)°, (x + 10)°, (x -10)°. Find the value of x.

A.

40

B.

60

C.

75

D.

80

E.

90

Correct answer is D

Sum of ∠s in a pentagon = (n - 2)180 = 540°
x° + 2x° + x° + 60° + x° + 10° + x° - 10° = 540°
6x° + 60° = 540°; x = 80°