Question

An arc of length $15$ cm subtends an angle of $45$ ${}^{\circ }$ at the centre of a circle. Find in terms of $\pi$ ,the radius of the circle.

Answer 1

Arc length$=\frac{\theta }{360°}\times 2\pi r=15cm$

$\Rightarrow \frac{\theta }{360°}\times 2\pi r=15cm\Rightarrow r=\frac{15\times 360°}{45\times 2\pi }=\frac{60}{\pi }cm$