Question

The length of minute hand on a wall clock is 14cm. find the areas swept by the minute hand in 30min

Answer 1

We know that the area of circle is A(circle)=(pie)r^2
and when the minute hand of a wall clock move for 30mn, we get a semicircle, yeild A(semicircle)=(pie)r^2(1/2). substitute all the known values we get, A(semicircle)= 307.72 cm^2

Answer 2

In 30 minutes the minute hand makes half a turn around the clock, so it sweeps half a circle.

Given the radius $r$, the area of a circle is $A = \pi r^2$

In this case, we're interested in half the area of a circle with radius 14cm, so we have

$A^* = \dfrac{\pi \cdot 14^2}{2} = \dfrac{196\pi}{2} = 98\pi$ cm squared.