Answer:
x =

Explanation:
Using Pythagoras' identity in both tight triangles.
First in the small triangle to find the third side ( hypotenuse ) h
h² = 1² + 1² = 1 + 1 = 2 ( take square root of both sides )
h =

Now use the identity in the larger right triangle
x² + h² = 4²
x² + (
)² = 16
x² + 2 = 16 ( subtract 2 from both sides )
x² = 14 ( take square root of both sides )
x =
