waecmaths question:
. Find the angle which an arc of length 22cm subtends at the centre of a circle of radius 15cm [Take $\pi =\tfrac{22}{7}$]
Option A:
70o
Option B:
84o
Option C:
96o
Option D:
156o
waecmaths solution:
$\begin{align} & l=2cm \\ & r=15cm \\ & l=\frac{\theta }{360{}^\circ }\times 2\pi r \\ & 22=\frac{\theta }{360{}^\circ }\times 2\times \frac{22}{7}\times 15 \\ & \theta =\frac{22\times 360{}^\circ \times 7}{2\times 22\times 15}=84{}^\circ \\\end{align}$
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