Answer:
Explanation:
All of the right triangles are similar. This means ...
long side / short side = x/2 = 25/x
Multiplying by 2x gives ...
x² = 25·2
x = (√25)(√2)
x = 5√2
_____
Additional comment
The "geometric mean" of 'a' and 'b' is √(ab). With this in mind, you can see that x is the geometric mean of the lengths 2 and 25. This is always true for this right-triangle geometry.
There are two other geometric mean relations in this geometry, having to do with the other possible ratios of sides. In effect, the length of a segment that touches the hypotenuse (longest side) of the triangle is the geometric mean of the two segments of the hypotenuse it touches.
Left side = √(2·27) = 3√6
Bottom side = √(25·27) = 15√3