The relative velocity of two bodies may be found out either graphically or analytically. But it has been experienced that analytical method is somewhat confusing. Sometimes, two bodies are moving along two inclined directions.
In such a case, the relative velocity of one with respect to the other may be found out by superimposing the actual velocity of any one of these two bodies in the opposite direction. It will be interesting to know that after superimposing the velocity, one of the bodies will be brought to rest. The resultant of two velocities on the second will give the required relative velocity.