To solve for this, we need to use Pythagorean Theorum.
Pythagorean Theorum is when we add the squares of the legs (A & B) to solve for the hypotenuse (C) or the side that's across from the 90 degree angle.
The formula for Pythagorean Theorum is A^2 + B^2 = C^2.
We have our two leg lengths, 15 and 36 (A & B).
Square 15 and 36.
15^2 = 225
36^2 = 1,296
Now that we have our side lengths, let's add them up.
225 + 1,296 = 1,521.
Now, to solve for C, we need to square root our sum.
The square root of 1,521 is 39.
Your hypotenuse is 39.
Your answer is C.) 39.
I hope this helps!