Answer is no, it is not a right triangle, it is an isosceles triangle
To prove it is a right triangle, use the Pythagorean theorem using 8 and 8 as your triangle legs (a and b) and 15 as your hypotenuse (c).
a^2 + b^2 = c^2
8^2 + 8^2 = c^2
64 + 64 = c^2
128 = c^2
Take square root of both sides
11.3 = c (15)
They do not equal so it is not a right triangle
Having two congruent sides of 8 it is an isosceles triangle. I did the math so that you can use it for any right triangle question