Use an alternative method to find the answer below and compare the results The ladder length represents the hypotenuse of a right triangle with a base of 9 and an unknown height (h). We can find that height by using the Pythagorean theorem.
9² + h² = 15²
81 + h² = 225
h² = 225 - 81 = 144
h = √144 = 12
12 ft + 6 ft = 18 ft
So, the ladder extends 12 feet up the side of the building. That is the height of the roof. The top of the flagpole is 6 feet above that, so the top of the flagpole is 18ft