Answer:
312.51 ft
Step-by-step explanation:
You would have to do tangent because if you add a triangle it gives you the opposite side length and you are trying to find the adjacent side lengths to the angle. It would look like this:
tan52=400/x
x*tan52=400*x
xtan52=400
xtan52/tan52=400/tan52
x=400/tan52
x=312.51 ft