Answer:
12² + 24² = 36²
144 + 576 = 1296
720 ≠ 1296
12, 24, 36: NOT a right triangle
16² + 9² = 11²
256 + 81 = 121
337 ≠ 121
16, 9, 11: NOT a right triangle
20² + 29² = 21²
400 + 841 = 441
1241 ≠ 441
20, 29, 21: NOT a right triangle
12.5² + 7.5² = 10²
156.25 + 56.25 = 100
212.5 ≠100
12.5, 7.5, 10: NOT a right triangle