Answer:
20m
Step-by-step explanation:
Given the height reached by the ball modelled by the equation
h = -d² + 8d+4.
The velocity of the balk at its maximum height is 0. Hence
v = dh/dd = 0
v = -2d + 8
0 = -2d+8
2d =8
d =8/2
d = 4
Substitute d = 4 into the equation to get the maximum height reached
h = -(4)² + 8(4)+4
h =-16+32+4
h = -16+36
h = 20
Hence the maximum height reached by the ball is 20m