Question

Find the number of right angles turned through by the hour hand of the clock when it goes from:
$12to9$

Answer 1

One complete revolution = $360˚$
There are twelve digits on a clock, this means $5mins=30˚$
Moving from $12to9$ there are nine digits, this means $9\times 30=270˚$
$\frac{270}{90}=3$
Thus, there are three right angles between $12$ and $9$