Crossing a Moat
The moat surrounding a castle is 18 ft wide and the wall by the moat of the castle is 24 ft high (see Fig. 9.32). If an invading army wishes to use a ladder to cross the moat and reach the top of the wall, how long must the ladder be?
The moat, the castle wall, and the ladder form a right triangle. The moat and the castle wall form the legs of the triangle (sides a and b), and the ladder forms the hypotenuse (side c). By the Pythagorean theorem,
Therefore, the ladder would need to be at least 30 ft long.