JAMB Mathematics Past Questions & Answers - Page 125

621.

In the figure, PT is tangent to the circle at U and QU/RS if TUR = 35º and SRU = 50º find x

A.

95o

B.

85o

C.

50o

D.

35o

Correct answer is A

Since QRU= Xo

RSU = Xo, But RSU = 180o - (50o + 35o)

= 180o - 85o

= 95o

x = 95o

622.

In the diagram, QP//ST:PQR = 34o qrs = 73o and Rs = RT. Find SRT

A.

68o

B.

102o

C.

107o

D.

141o

Correct answer is B

Construction joins R to P such that SRP = straight line

R = 180o - 107o

< p = 180o - (107o - 34o)

108 - 141o = 39o

Angle < S = 39o (corr. Ang.) But in \(\bigtriangleup\)SRT

< S = < T = 39o

SRT = 180 - (39o + 39o)

= 180o - 78o

= 102o

623.

In the diagram, O is the centre of the circle and POQ a diameter. If POR = 96o, find the value of ORQ.

A.

84o

B.

48o

C.

45o

D.

42o

Correct answer is B

OQ = OR = radii

< ROQ = 180 - 86 = 84o

\(\bigtriangleup\)OQR = Isosceles

R = Q

R + Q + 84 = 180(angle in a \(\bigtriangleup\))

2R = 96 since R = Q

R = 48o

ORQ = 48o

624.

In the diagram, PQRS is a circle with O as centre and PQ/RT. If RTS = 32°. Find PSQ

A.

32o

B.

45o

C.

58o

D.

90o

Correct answer is C

< PSO = \(\frac{1}{2}\) < SOQ = \(\frac{1}{2}\)(180) = 90°

< RTS = < PQS = 32° (Alternative angle)

< PSQ = 90 - < PSQ = 90° - 32°

= 58°

625.

PQRST is a regular pentagon and PQVU is a rectangle with U and V lying on TS and SR respectively as shown in the diagram. Calculate TUP

A.

18o

B.

54o

C.

90o

D.

108o

Correct answer is B

The total angle in a regular pentagon = \((2(5) - 4) \times 90\)

= \(6 \times 90 = 540°\)

Each interior angle = \(\frac{540}{5} = 108°\)

While the interior of a quadrilateral = \(\frac{360}{4} = 90°\)

\(PTU + TPU + TUP = 180°\)

\(108° + (180° - 90°) + TUP = 180°\)

\(TUP = 180° - (108° + 18°) = 54°\)