I am having some serious difficulety determining (b) the speed upon impact
In Fig. 4-36, a stone is projected at a cliff of height h with an initial speed of 48.0 m/s directed at an angle θ0 = 50.0° above the horizontal. The stone strikes at A, 5.21 s after launching. Find (a) the height h of the cliff, (b) the speed of the stone just before impact at A, and (c) the maximum height H reached above the ground.