3 particles A,B,C are projected from a point above the ground level.A launches horizontally with a velocity ofUand B, was launches $\displaystyle 90-\theta$from vertical with the velocity ofWand C was launches vertically with the velocity ofV.Using the relative velocity, If $\displaystyle \frac{cos\theta}{U}+\frac{sin\theta}{V}=\frac{1}{W }$,Show that The particles A,B,C are in a straight line??

In this case Give me hint to use Relative velocity>>><<<<