Use Pythagorean Theorem:
square the shorter side lengths and add them together....then see if that sum equals the square of the longer side.....try it!
8 -15 - 17 IS a right triangle....you try the others
8^2 + 15^2 =? 17^2
64 + 225 =? 289
289 = 289 yes, it is a right triangle !