Which set of side lengths defines a right triangle?

A.

7, 9, 13

B.

5, 12, 14

C.

8, 15, 17

D.

9, 12, 14

If you have a lot of Pythagorean triples memorized, then you'd probably know immediately, but if not, then you can use the Pythagorean Theorem to calculate each one:

A.: 7^2+9^2=49+81 which is not equal to 13^2, or 169

B.: 5^2+12^2=25+144 which is not equal to 14^2, or 196

C.: 8^2+15^2=64+225=17^2=289

D.: 9^2+12^2=81+144 which isn't equal to 14^2, or 196

Therefore, the correct answer is C.