JAMB Mathematics Past Questions & Answers - Page 289

1,441.

A point P moves so that its equidistant from point L and M. If LM is16cm, find the distance of P from LM when P is 10cm from L

A.

12cm

B.

10cm

C.

8cm

D.

6cm

Correct answer is D

p from LM = \(\sqrt{10^2 - 8^2}\) 

= \(\sqrt{36}\) = 6cm

1,442.

The angle between the positive horizontal axis and a given line is 135°. Find the equation of the line if it passes through the point (2,3)

A.

x - y = 1

B.

x + y = 1

C.

x + y = 5

D.

x - y = 5

Correct answer is C

m = tan 135° = -tan 45° = -1

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

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

= y - 3 = -(x - 2)

= -x + 2

x + y = 5

1,443.

A cone with the sector angle of 45° is cut out of a circle of radius r of the cone.

A.

\(\frac{r}{16}\) cm

B.

\(\frac{r}{6}\) cm

C.

\(\frac{r}{8}\) cm

D.

\(\frac{r}{2}\) cm

Correct answer is C

The formula for the base radius of a cone formed from the sector of a circle = \(\frac{r \theta}{360°}\)

= \(\frac{r \times 45°}{360°}\)

= \(\frac{r}{8} cm\)

1,444.

An arc of a circle subtends an angle 70° at the centre. If the radius of the circle is 6cm, calculate the area of the sector subtended by the given angle.(\(\pi\) = \(\frac{22}{7}\))

A.

22cm2

B.

44cm2

C.

66cm2

D.

88cm2

Correct answer is A

Area of a sector = \(\frac{\theta}{360°} \times \pi r^{2}\)

r = 6cm; \(\theta\) = 70°.

Area of the sector = \(\frac{70}{360} \times \frac{22}{7} \times 6^{2}\)

= \(22 cm^{2}\)

1,445.

A chord of a circle of a diameter 42cm subtends an angle of 60° at the centre of the circle. Find the length of the mirror arc

A.

22cm

B.

44cm

C.

110cm

D.

220cm

Correct answer is A

Diameter = 42cm

Length of the arc = \(\frac{\theta}{360°} \times \pi d\)

= \(\frac{60}{360} \times \frac{22}{7} \times 42cm\)

= \(22cm\)