9514 1404 393
Answer:
2
Step-by-step explanation:
y is the geometric mean of the segment lengths.
y = √(4·1)
y = 2
_____
You can also get there by considering the similarity of the triangles:
short side / long side = y/4 = 1/y
y^2 = 4 . . . . . . . multiply by 4y\
y = √4 = 2 . . . . take the square root
