9514 1404 393
Answer:
9.9
Explanation:
The applicable geometric mean rule tells you ...
y = √(9(9+2)) = √99
y ≈ 9.9
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Additional comment
In this geometry, the right triangles are similar. Ratios of corresponding sides are equal.
hypotenuse/long side = y/9 = (9+2)/y
y^2 = (9)(11)
y = √99 . . . . as above
The long leg is the geometric mean of the (adjacent) long segment and the full hypotenuse.