A ladder 13 m long rests against a wall with foot 5 m from the wall. The ladder reaches a height of

1. Hypotenuse = 13 m, one leg = 5 m, other leg = h. 2. h^2 = 13^2 - 5^2 = 169 - 25 = 144. 3. h = 12 m. 4. So the ladder reaches 12 m up the wall. _Source: Selina Concise Mathematics Class 9, Ch on Pythagoras Theorem (Mistral OCR'd PDF), section on word problems_