1) The vertex form of the function reveals when the hovercraft reached its highest point:
h(t)=-4\left(t-1\right)^2+36h(t)=−4(t−1)
2
+36h, left parenthesis, t, right parenthesis, equals, minus, 4, left parenthesis, t, minus, 1, right parenthesis, squared, plus, 36
2) The hovercraft reached its highest point 111 minute after takeoff.