Mr. Weiser is making flags of various countries for an international convention. On the flag of Namibia, he sees that the red diagonal band divides the flag into a blue triangle at the top and a green triangle at the bottom. He measures the three sides of the triangle to be 66 centimeters, 112 centimeters, and 130 centimeters. What must be true to prove that the green triangle on the flag of Namibia is a right triangle?