In x-y plane, there is a right triangle ABC (∠B=90o). If the length of AC is 25 and the slope of line segment AC is 4/3, what is the length of AB? Choose the correct choice from the following choices:
A) 12
B) 18
C) 24
D) 20
E) 40

Rationale: "slope = change in vertical direction / change in horizontal direction = 4 / 3 change in vertical direction = 4 x = ab change in horizontal direction = 3 x = bc ab ^ 2 + bc ^ 2 = 25 ^ 2 16 x ^ 2 + 9 x ^ 2 = 625 25 x ^ 2 = 625 x ^ 2 = 25 x = 5 therefore ab = 5 * 4 = 20 answer : d"
Answer: D