Final answer:
Marc should fasten the bracket approximately 5.7 inches below the corner.
Step-by-step explanation:
To find the distance below the corner where Marc should fasten the bracket, we need to use the Pythagorean theorem. Let's assume the distance from the corner to each end of the bracket is x inches. This forms a right triangle with one leg as x inches, another leg as x inches, and the hypotenuse as 8 inches. Using the Pythagorean theorem, we can write:
x^2 + x^2 = 8^2
2x^2 = 64
x^2 = 32
x = sqrt(32)
x ≈ 5.7 inches
Therefore, Marc should fasten the bracket approximately 5.7 inches below the corner.