JAMB Mathematics Past Questions & Answers - Page 321

1,601.

If angle \(\theta\) is 135°, evaluate cos\(\theta\)

A.

\(\frac{1}{2}\)

B.

\(\frac{\sqrt{2}}{2}\)

C.

\(-\frac{\sqrt{2}}{2}\)

D.

\(-\frac{1}{2}\)

Correct answer is C

\(\theta\) = 135°

Cos 135° = Cos(90 + 45)°

= cos90° cos45° - sin90° sin45°

= 0cos45° - (1 x \(\frac{\sqrt{2}}{2}\))

= \(-\frac{\sqrt{2}}{2}\)

1,602.

Find the equation of the line through the points (-2, 1) and (-\(\frac{1}{2}\), 4)

A.

y = 2x - 3

B.

y = 2x + 5

C.

y = 3x - 2

D.

y = 2x + 1

Correct answer is B

\(\frac{y - y_1}{x - x_1}\) = \(\frac{y_2 - y_1}{x_2 - x_1}\)

\(\frac{y - 1}{x -  -2}\) = \(\frac{4 - 1}{-\frac{1}{2} + 2}\)

= \(\frac{y - 1}{x + 2}\) = \(\frac{3}{\frac{3}{2}}\)

y = 2x + 5

1,603.

The distance between the point (4, 3) and the intersection of y = 2x + 4 and y = 7 - x is

A.

\(\sqrt{13}\)

B.

\(3\sqrt{2}\)

C.

\(\sqrt{26}\)

D.

\(10\sqrt{5}\)

Correct answer is B

P1 (4, 3), P2 (x, y)

y = 2x + 4 .....(1)

y = 7 - x .....(2)

Substitute (2) in (1)

7 - x = 2x + 4

7 - 4 = 2x + x

3 = 3x

x = 1

Substitute in eqn (2)

y = 7 - x

y = 7 - 1

y = 6

P2 (1, 6)

Distance between 2 points is given as

D = \(\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}\)

D = \(\sqrt{(1 - 4)^2 + (6 - 3)^2}\)

D = \(\sqrt{(-3)^2 + (3)^2}\)

D = \(\sqrt{9 + 9}\)

D = \(\sqrt{18}\)

D = \(\sqrt{9 \times 2}\)

D = \(3\sqrt{2}\)

1,604.

The gradient of the straight line joining the points P(5, -7) and Q(-2, -3) is

A.

\(\frac{1}{2}\)

B.

\(\frac{2}{5}\)

C.

\(-\frac{4}{7}\)

D.

\(-\frac{2}{3}\)

Correct answer is C

PQ = \(\frac{y_1 - y_0}{x_1 - x_0}\) = \(\frac{-3 - (-7)}{-2 - 5}\) = \(\frac{-3 + 7}{-2 - 5}\) = \(\frac{4}{-7}\)

1,605.

Calculate the volume of a cuboid of length 0.76cm, breadth 2.6cm and height 0.82cm.

A.

3.92cm3

B.

2.13cm3

C.

1.97cm3

D.

1.62cm3

Correct answer is D

Volume of cuboid = L x b x h

= 0.76cm x 2.6cm x 0.82cm

= 1.62cm3