This is just an application of Pythagoras' theorem. The ladder is the hypotenuse of a right triangle formed by the building. The Hypotenuse is 15 ft, and side a (the floor,) is 6 ft. PLugging this into the theorem, we get 15^2 = 6^2 + b^2 225 = 36 + b^2 189 = b^2 b is approximately 13.7478
<span>The ladder is the hypotenuse of a right triangle. one side=6ft Height=. </span><span>EQUATION: x^2+6^2=15^2 x^2=189 x=13.7 ft. (the ladder reaches 13.7 ft. up the wall)</span>