Question

The large hand of a clock is 42 cm long.How many centimetre does its extremity move in 20 minutes?

Answer 1

d=pi×r×degree/180
=22/7×42×120/180
=88 cm

hope this will help you.

Answer 2

Answer:

The hand of the clock moves 88 cm in 20 minutes.

Step-by-step explanation:

In an hour or 60 minutes, the large hand performs a complete circle of 360 degree.  

Therefore, in a time span of 20 minutes or One third of one Hour, you will get 120 degree or $\bold{\frac{2 \pi}{3}}$

To find the count of centimeters it is required to move the hand, we first frame the formula i.e. to find the length of the “arc” formed by circular movement of the hand

$l=r \theta=42\left(\frac{2 \pi}{3}\right)=14\left(\frac{44}{7}\right)=88 \mathrm{cm}$

Therefore, the extremity moves 88 cm in twenty minutes.