NECO 2024 · Paper 1 · Q40

Circle geometry
Plane mensuration

Calculate the length of an arc which subtends an angle of $66^\circ$ at the centre of a circle of radius $8\text{ cm}$ , correct to one decimal place.

Worked solution (try it first)

Arc length is $\frac{\theta}{360^\circ} \times 2\pi r$ .
Put in $\theta = 66^\circ$ and $r = 8$ : arc $= \frac{66}{360} \times 2 \times \frac{22}{7} \times 8$
$= 9.219$ cm.
To one decimal place the arc is 9.2 cm, option D.

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