Answer: 12
Explanation:
Although you have not included which value is the hypotenuse or if they are legs, I will assume the hypotenuse is 20, due to the triangle appearing to be a multiple of the standard 3-4-5 triangle.
The pythagorean theorem is a^2+b^2=c^2, where a and b are the legs and c is the hypotenuse. Thus, plug in the values to get: