In every right triangle, you have the following identites:

Where
is one of the acute angles,
is the leg opposite to the angle,
is the leg adjacent to the angle and
is the hypothenuse.
In this case, we know that the adjacent leg is 100ft long, so we can use the second formula to compute the hypothenuse:

Now let's use the first equation to compute the length of the opposite leg, i.e. the one you're interested in:

Note that the ratio between the sine and the cosine is the tangent:

If you ask for the tangent of 37 to a calculator, you get

So, you have

Which rounded to the nearest tenth is 75.36