Answer:
A is not a right triangle
B is a right triangle
Step-by-step explanation:
A.
6^2 = 36
12^2 = 144.
36 + 144 = 180
15^2 = 225
180 ≠ 225, so it is not a right triangle
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B.
5^2 = 25
12^2 = 144
25 + 144 = 169
13^2 = 169
169 = 169, so it is a right triangle