Answer:
Depends if you are averaging C or not.
Explanation:
Use the pythagorean theorem to solve this.
c = √a^2 + b^2
A and B should be two of your sides and C should equal your third side. If C is incorrect, it is not a right triangle. I plugged in 7 for A and 8 for B. The answer was about 10.63. If you are supposed to round C then yes, it is a right triangle. If you aren't supposed to round C (probably not) then no, It isn't a right triangle.