The three missing lengths are the left hypotenuse, x, the middle altitude, y, and the right hypotenuse, z.
9/y = y/16
y^2 = 9 * 16
y^2 = 144
y = 12
9^2 + 12^2 = x^2
x^2 = 225
x = 15
12^2 + 16^2 = z^2
z^2 = 400
z = 20
From left to right, the sides measure 15, 12, and 20 units.
the answer is the first one A
