The time required for the maximum height to be attained is calculated by differentiating the given equation and equating the derivative to zero.Â
                  h(t) = -16t² + 576t
              dh(t) / dt = 0 = (-16)(2)t + 576
The value of t from the equation is 18. Thus, after 18 seconds the projectile reaches its maximum height.Â
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