Question

A firefighter in training leans a 21-foot extension ladder against an office building. How far from the building should the ladder be placed if the firefighter wants to reach a window that is 15 feet above the ground?

Answer 1

Let 21 = Hypotenuse Let 15 = One leg on the y-axis. 
Draw triangle. a^2+b^2 = c^2 
a^2 = c^2 - b^2 a = sqrt(c^2-b^2) 
sqrt(21^2 - 15^2) = ~14.7 ft 
...|\ ...|..\ b.|....\ 21 ...|.....\ ...|____\ .......a