If the horizontal component of intial velocity is 35.7, then the vertcal component is 35.7 tan(37). You can then calculate that the vertical velocity at each time t seconds after being fired is - 9.8t+ 35.7 tan(37) while the horizontal velocity is constant at 35.7.

The vertical height of the cannonball, taking its initial position as h=0 is . The ground at the bottom of the cliff is at h= -40 so you can find thetimethe cannonball hits the ground by solving .

You can then calculate the velocity vector by putting that time into v_x= 35.7 and .

The angle at which the cannonball hits the ground is given by .