AD = 42-x
The bisector of an angle of a triangle divides the opposite side into segments that are proportional to the adjacent sides ⇒
AB/BC = AD/DC
36/27 = (42-x)/x
36x = 27(42-x)
36x = 1134 - 27x
36x + 27x = 1134
63x = 1134
x = 1134/63
x = 18
.74% ar least or else he would crumble

Using the quadratic formula we get

Therefore the tennis ball is at least 15 feet above the ground from 0.5 seconds to 2.04 seconds