Answer:
Yes, this is a right triangle.
Step-by-step explanation:
If you look more closely, you can notice that it is a 3-4-5 Pythagorean triple and it was multiplied by 3 to get 9-12-15.
Or you can do it using the Pythagorean Theorem directly:
9^2 + 12^2 = 15^2
and that is true.
