Question

Find the angle subtended at the centre of a circle of radius $5$ cm by an arc of length $\left(\frac{5\pi }{3}\right)$ cm.

Answer 1

Arc length$=\frac{\theta }{360°}\times 2\pi r\Rightarrow \frac{5\pi }{3}=\frac{\theta }{360°}\times 2\pi \times 5$

$\theta =\frac{360°\times 1}{2\times 3}=60°$