-- This is a right triangle. So you KNOW that
(one leg)² + (other leg)² = (hypotenuse)²
-- Also, since the acute angles are equal, the legs must be equal ... both x .
-- Plugging into the formula:
x² + x² = (4)²
2x² = (4)²
2x² = 16
x² = 8
√x² = √8
x = √8
x = √(4 · 2)
x = √4 · √2
x = 2 · √2
(That's choice D)
