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 39
we check the equality of the equation
39² = 15² + 36²
1521 = 225 + 1296
1521 = 1521
Equality was fulfilled so it is a right triangle