JAMB Mathematics Past Questions & Answers - Page 128

636.

In the figure above, find the value of y

A.

28o

B.

122o

C.

150o

D.

152o

Correct answer is B

ADB = 180o - 152o = 28o

28o + y + 30o = 180o

y = 180o - 58o

= 122o

637.

PMN and PQR are two secants of the circle MQTRN and PT is a tangent. If PNR = 110o and PMQ = 55o, find MPQ

A.

40o

B.

30o

C.

25o

D.

15o

Correct answer is D

PQM = 110o(Ext. < of a cyclic quad)

MPQ = 180o - (110 + 55)

= 180o - 165o

= 15o

638.

PMN and PQR are two secants of the circle MQTRN and PT is a tangent. If PM = 5cm, PN = 12cm and PQ = 4.8cm, calculate the respective lengths of PR and PT in centimeters

A.

7.3, 5.9

B.

7.7, 12.5

C.

12.5, 7.7

D.

5.9, 7.3

Correct answer is C

\(\frac{PQ}{PN} = \frac{PM}{PR} = \frac{QM}{NR}\)

\(\frac{4.8}{12} = \frac{5}{PR}\)

PR = \(\frac{5 \times 12}{4.8} = \frac{50}{4}\)

= 12.5

\(\frac{PQ}{PN} = \frac{PM}{PT} = \frac{TM}{NT}\)

\(\frac{PT}{12} = \frac{5}{PR}\)

PT2 = 60

PT = \(\sqrt{60}\)

= 7.746

= 7.7

639.

In the figure above, Find the value of x

A.

130o

B.

110o

C.

100o

D.

90o

Correct answer is A

No explanation has been provided for this answer.

640.

Find the curved surface area of the frustrum in the figure

A.

16\(\pi \sqrt{10}\)cm2

B.

20\(\pi \sqrt{10}\)cm2

C.

24\(\pi \sqrt{10}\)cm2

D.

36\(\pi \sqrt{10}\)cm2

Correct answer is B

\(\frac{x}{4} = \frac{6 + x}{6}\)

6x = 4(6 + x) = 24 + 4x

x = 12cm 

 CSA = \(\pi RL - \pi rl\)

= \(\pi (6) \sqrt{{18^2} + 6^2} - \pi \times 4 \times \sqrt{{12^2} + 4^2}\)

= 6\(\pi \sqrt{360} - 4 \pi \sqrt{160}\)

= 36\(\pi \sqrt{10} - 16 \pi \sqrt{10}\)

= 20\(\pi \sqrt{10}\)cm2