Question

Find the angle subtended at the centre of a circle of radius ${}^{\prime }{a}^{\prime }$ by an arc of length $\left(\frac{a\pi }{4}\right)$ cm.

Answer 1

Arc length$=\frac{\theta }{360°}\times 2\pi r=\frac{a\pi }{4}$

$\Rightarrow \frac{\theta }{360°}\times 2\pi \times a=\frac{a\pi }{4}\Rightarrow \theta =\frac{360°}{8}=45°$