Because the triangle ABC is isosceles, the leg of the triangle has the same length. For example, the length of one leg is a, then the other leg is a too.
Input the numbers to pythagorean formula
a² + b² = c²
a² + a² = 8²
2a² = 64
a² = 64/2
a² = 32
a = √32
a = √16 × √2
a = 4√2
The length of each leg is 4√2 inches