Answer:
a=169 ft
Explanation:
Here you are given the angle 25, and the opposite and hypotenuse values.
Opposite/Hypotenuse: the sin(angle 25)=a/400ft.
We need to solve for a, so lets multiply 400 to the other side:
400(sin25)=a. Plug this into your calculator and you will get the answer: a=169.04 ft