You can use the pythagoras’ theorem and just look at one right triangle.
The dimensions for one of the right triangles is (x/2), 8, and square root of 80.
a^2 + b^c = c^2
when c is the square root of 80.
Plug everything in
(x/2)^2 + 8^2 = (square root of 80)^2
That is equivalent to
((x^2)/4) + 64 = 80
Solve for x
((x^2)/4) = 16
Multiple by 4 on each side
x^2 = 64
Take the square root and you have you’re final answer
x = 8