Answer:
B. 9 feet
Explanation:
Using the Pythagorean theorem, the height from the ground to the window (12 ft) is one leg of the right triangle and the length of the ladder while propped against the house (15 ft) is the hypotenuse. Therefore, we need to find the other leg of the right triangle represented by how far the base of the ladder is placed from the base of the house:
a² + b² = c²
12² + b² = 15²
144 + b² = 225
b² = 225 – 144
b² = 81
b = √81 = 9
Therefore, the answer is (B) 9 feet.