Help plz. I don't understand

Answer:
Step-by-step explanation:
The illustration is unclear. Is y the base of both triangles, or is it the base of the triangle on the right?
I'll assume that y is the base of the triangle on the right.
The triangle on the left is a 45-45-90 triangle. The lengths of the sides are in the ratio 1:1:√2, so the length of the vertical leg is 8/√2.
The triangle on the right is a 30-60-90 triangle. The lengths of the sides are in the ratio 1:√3:2.
The side opposite the 30° angle is 8/√2, so the side opposite the 60° angle is 8√3/√2 = 4√6, and the side opposite the 90° angle is 2×8/√2 = 8√2.