For this case we can model the problem as a rectangle triangle.
We have the hypotenuse and the angle.
We want to find the height.
For this, we use the following trigonometric relationship:
sine (x) = C.O / h
Where,
x: angle
C.O: opposite leg
h: hypotenuse
Clearing C.O we have:
C.O = 85 * sine (45)
C.O = 60.1040764
Round to the nearest tenth of a foot:
C.O = 60 feet
Answer:
the top of the tree house is 60 feet high
