A ladder is leaning against a building. The base of the ladder is 5 feet away from the wall, and the ladder reaches a height of 12 feet up the wall. How long is the ladder?
✓ Correct Answer: Option B
Use the Pythagorean theorem, a² + b² = c². 5² + 12² = c². 25 + 144 = c². 169 = c². Therefore, c = √169 = 13 feet.