Question

Large hand of a clock is $21$ cm long. How much distance does its extremity move in $20$ minutes?

Answer 1

Distance cover in $20$ minutes $=\frac{\theta }{{360}^0}\times 2\pi r$

Now, in $60$ min $-$ ${360}^0$

$1$ min $-$ ${60}^0$

$20$ min $-$ ${120}^0$

$\therefore$ Distance $=\frac{{120}^0}{{360}^0}\times 2\times \frac{22}{7}\times 21=44cm$