Your medieval history class is constructing a trebuchet, a catapult-like weapon for hurling stones at enemy castles. The plan is to launch stones off a high cliff, with initial speed . Some members of the class think a 45 degree launch angle will give the maximum range, but others claim the cliff height makes a difference. Find an expression for the angle that will maximize the range of a projectile launched with speed from height above level ground. Express your answer in terms of the variables, and appropriate constants.