A tennis ball is thrown toward a vertical wall with a speed of 21.0 m/s at an angle of 40.0° above the horizontal. The horizontal distance between the wall and the point where the tennis ball is released is 23.0 m.
a. At what height above the point of release does the tennis ball hit the wall?
b. Has the tennis ball already passed the highest point on its trajectory when it hits the wall? Justify your answer.