I have no idea how to start this, was thinking about the displacement would have to be the same but don't know where to go from there.
A cannon fires two missiles with speed $v_0$=250$ms^-1$, the first at angle $\alpha_1$=60 degrees to the horizontal and the second one $\alpha_2$=45 degrees. Show that for the missiles to collide in mid-air the time interval between the shots must be equal to:
$\Delta$$t$ = (2$v_0$/$g$)($sin(\alpha_1 -\alpha_2)$/($cos\alpha_1$ + $cos\alpha_2$))