A cow is tied to a post with a rope of `20 m` long .If it moves along a circular path by keeping the rope always tight. Find how far it will have gone when the rope has reached an angle of `90^(circ)`

Explanation

r=20 m , theta=90^(circ)=(pi)/(2).

.I=r_(theta)^(prime)=20 xx (pi^(prime))/(2)=10 pi m=31.4 m , therefore. Distance travelled by cow=31.4 m.