Which statement explains the Pythagorean Theorem?

a. If a triangle is a right triangle, then the sum of the squares of the longest leg and the hypotenuse is equal to the square of the third side.

b. If a triangle is a right triangle, then the sum of the squares of the legs is equal to the square of the hypotenuse.

c. If all angles in a triangle are equal measure, then the length of all sides will be equal.

d. If the interior angles of a triangle add up to 180, then the sum of the legs of the triangle is equal to the square to the square of the hypotenuse

b. If a triangle is a right triangle, then the sum of the squares of the legs is equal to the square of the hypotenuse.