To check which set does not make a right triangle, let us check if each set is a Pythagorean triplet:
A) 3, 4, 5
(3)^2+(4)^2=(5)^2
= 9+16=25
= 25=25
B) 5, 12, 13
(5)^2+(12)^2=(13)^2
= 25+144=169
= 169=169
C) 9, 40, 41
(9)^2+(40)^2=(41)^2
= 81+1600=1681
= 1681=1681
D) 7, 8, 15
(7)^2+(8)^2=(15)^2
= 49+64=225
= 113≠225
Thus, the set of side measures 7, 8, 15 does not form a Pythagorean Triplet, and thus not a right triangle.