The Pythagorean Theorem states that in a right triangle, the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the lengths of the other two sides. In this case, we are given the values of b and c, which are the two sides of the right triangle. By substituting the values into the formula a^2 = c^2 - b^2, we can solve for a. Plugging in the given values, we get a^2 = 10^2 - 6^2, which simplifies to a^2 = 100 - 36. Therefore, a^2 = 64, and taking the square root of both sides, we find that a = 8.