A parrticle projected with velocity u strikes at right angles a plane through the point of projection inclined at angle `beta` to the horizon. Show that the height of the point struck above the horizontal plane through the point of projection is `(2u^2)/g . (sin^2 beta)/(1+3 sin^2 beta)` and that the time of flight up to that instant is `t=(2u)/(g sqrt(1+3 sin^2 beta))`.