Answer:
Yes, is a right triangle
Explanation:
To know if you can build a right triangle with those sides we have to make the following equality
h² = l1² + l2²
The hypotenuse is always the longest side so it should be 15
we check the equality of the equation
15² = 9² + 12²
225 = 81 + 144
225 = 225
Equality was fulfilled so it is a right triangle