Question

Mr Beni wants to construct circular cycling track for the residents.Outer radius of the circular track is 21 m and the inner radius 17.5 m. Find the area of the track.
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Answer 1

area of ring =

$\pi( {r}^{2} - {r2}^{2} ) \\ \frac{22}{7} (21 - 17.5) \\ = \frac{22}{7} \times 3.50 \\ = 11sq \: m$