JAMB 1993 · UME · Q37

Plane mensuration

Find the area of the sector of a circle with radius 3 m if the angle of the sector is $60^\circ$ .

Worked solution (try it first)

Area of a sector $= \frac{\theta}{360} \times \pi r^2$ .
Here $\frac{60}{360} = \frac16$ and $r^2 = 9$ .
So the area is $\frac16 \times 9\pi = 1.5\pi$
$\approx 4.71\text{ m}^2$ .
To one decimal place that is $4.7\text{ m}^2$ , option C.

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