JAMB Mathematics Past Questions & Answers - Page 145

721.

If PN is perpendicular to QR, find the value of tan x.

A.

\(\frac{5}{9}\)

B.

\(\frac{3}{5}\)

C.

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

D.

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

E.

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

Correct answer is B

By Pythagoras ON = 4

NR = 5

Tan x = \(\frac{3}{5}\)

722.

The area under the speed time graph given the total distance covered by car. What is the average velocity to two places of decimals?

A.

17.72 meter/sec.

B.

21.67 meters/sec

C.

2.5 meter/sec.

D.

20.45 meters/sec.

E.

13.33 meter/sec.

Correct answer is D

Time(sec) areas of the three sides are \(\frac{1}{2}\) x 2 x 20 = 20 x 2 = 40

\(\frac{1}{2}\) x 4 x 20 = 40

40 + 40 = 80

vel. = \(\frac{80}{4}\)

20 + 0.45 = 20.45 meter/sec.

723.

Find x in the diagram below.

A.

3\(\sqrt{3}\)

B.

\(\frac{3(\sqrt{3} - 1)}{\sqrt{3} + 1}\)

C.

\(\frac{(\sqrt{3} - 1)}{\sqrt{3} + 1}\)

D.

\(\frac{3 - 1}{\sqrt{3} + 1}\)

Correct answer is B

\(\frac{x + 3}{sin 60^o}\) = \(\frac{x}{sin 306o}\)

3sin 30o = x sin 60o - x sin 30o

= x(sin 60o - sin 30o)

but sin 30o = \(\frac{1}{2}\)

sin 60o = \(\frac{3}{2}\) = \(\frac{3(\sqrt{3} - 1)}{\sqrt{3} + 1}\)

724.

PQ is parallel to RS. Calculate the value of x.

A.

20o

B.

40o

C.

60o

D.

80o

E.

100o

Correct answer is B

< D = 180o - 100v

= 80o (< on a str. line)

< s = 60o - alternate angle

x = 180o - (80o + 60o)

180o - 140o = 40o

725.

In the parallelogram PQRS, PE is perpendicular to QR. Find the area of the parallelogram.

A.

60cm2

B.

65cm2

C.

72cm2

D.

132cm2

E.

156cm2

Correct answer is D

By Pythagoras, PE\(^2\) = 12\(^2\) - 5\(^2\)

= 144 - 25 = 119

h = PE\(^2\) = √119 = 10.9 ≈ 11cm,

Area of 11gm = b x h

QR = b =(5 + 7)cm = 12cm

area = 12 x 11

= 132cm\(^2\)