JAMB Mathematics Past Questions & Answers - Page 134

666.

In the figure, find angle x

A.

100o

B.

120o

C.

60o

D.

110o

E.

140o

Correct answer is E

In the figure, angle x = 20o + 80o + 40o

= 140o

667.

In the figure, the area of the shaded segment is

A.

3\(\pi\)

B.

9\(\frac{\sqrt{3}}{4}\)

C.

3 \(\pi - 3 \frac{\sqrt{3}}{4}\)

D.

\(\frac{(\sqrt{3 - \pi)}}{4}\)

E.

\(\pi + \frac{9 \sqrt{3}}{4}\)

Correct answer is C

Area of sector = \(\frac{120}{360} \times \pi \times (3)^2 = 3 \pi\)

Area of triangle = \(\frac{1}{2} \times 3 \times 3 \times \sin 120^o\)

= \(\frac{9}{2} \times \frac{\sqrt{3}}{2} = \frac{9\sqrt {3}}{4}\)

Area of shaded portion = 3\(\pi - \frac{9\sqrt {3}}{4}\)

= 3 \(\pi - 3 \frac{\sqrt{3}}{4}\)

668.

The figure is an example of the construction of a

A.

perpendicular bisector of a given straight line QR

B.

perpendicular from a given point to a given line QR

C.

perpendicular to a line from a given point P on that line

D.

given angle

Correct answer is B

QR is a given line and P is a given point. The construction is the perpendicular from a given point P to a given line QR

669.

In the figure, find the value of x

A.

110o

B.

100o

C.

90o

D.

80o

Correct answer is C

Z = X = Y = 180o .........(i)

2Z + Y + Y = 190 = 2Z + 2Y = 180

Z + Y = 90o........(ii)

hence x + (z + y) = 180

x + 90o = 180o

x = 180o - 90o

= 90o

670.

Three angles of a nonagon are equal and the sum of six other angles is 1110o. Calculate the size of one of the equal angles.

A.

210o

B.

150o

C.

105o

D.

50o

Correct answer is D

Sum of interior angles of any polygon is (2n - 4) right angle; n angles of the nonagon = 9

where 3 are equal and 6 other angles = 1110o

( 2 x 9 - 4)90o = (18 - 4)90o

= 14 x 90o = 1260o

9 angles = 12600, 6 angles = 1110o

Remaining 3 angles = 1260o - 1110o = 150o

size of one of the3 angles \(\frac{150}{3}\) = 50o