Answer:
A)
Step-by-step explanation:
To start, notice that the triangle with legs of x and 16 is similar to the triangle with legs of 9 and x. Then, we get the equation 9/x = x/16, so x^2 = 144 and x = 12 or A).
Note: This generalizes to all right triangles, where the altitude squared is the product of the length of the two segments it splits the hypotenuse into.
