If ac = 36 and bc = 18, find ad. round to the nearest tenth, if necessary.

Using: a^2 + b^2 = c^2 (pythagoras theorem)
where 'a' and 'b' are the legs of a right triangle, c is the hypotenuse
compare the triangle I just drew to the triangle you have for your problem
you'll see that a = unknown b = 18 c = 36
a=18sqrt3
=31.2

Ive seen this before! the answer is b