The square of the resultant of two equal forces acting at a point is equal to three times their product. Find the angle between them.

Explanation

Given `P=P, Q=P,R^2=3P^2`
We know that `R^2=p^2+Q^2+2PQcostheta`
i.e., `3P^2=P^2+P^2+2P^2costheta`
i.e., `P^2=2P^2costheta`
`:." " 2costheta=1`
Angle between the two forces `=60^(@)`