一道英文的数学题…… 没看懂

题目

一道英文的数学题…… 没看懂
A child swings back and forth,reaching a maximum angle of 32° with the vertical.
The swing is 3.4 m long and 0.75 m from the ground when at rest.
What maximum height above the ground does the child reach.
“The swing is 3.4 m long and 0.75 m from the ground when at rest.”

答案

秋千长3.4m,静止时距离地面0.75m.
计算：
0.75+（3.4-3.4*cos32）