Question

A pendulum swings through on angle of ${30}^{\circ }$ and describes an arc 8.8 cm in length. Then the length of pendulum in cm is ___ .

Answer 1

Let r be the length of the pendulum

$\angle$AOB = 30 ${}^{\circ }$

Length of an arc of a sector of an angle $\theta$ = $\frac{\theta }{360}$× 2$\pi$r

r = $\frac{30}{360}$× 2$\pi$r

r = $\frac{8.8\times 6}{\pi }$

r = 16.8 cm