question_answer 15)

A 15 m long ladder reached a window 12 m high from the ground on placing it against a wall at a distance a. Find the distance of the foot of the ladder from the wall.

Answer:

                Let the distance of the foot of the ladder from the wall be \[a\] m. Then, \[{{a}^{2}}+{{12}^{2}}={{15}^{2}}\] \[\left| \text{By Pythagoras Property} \right.\] \[\Rightarrow \]         \[{{a}^{2}}+144=225\] \[\Rightarrow \]         \[{{a}^{2}}=225-144\] \[\Rightarrow \]         \[~a=81\] \[\Rightarrow \]         \[a=9\] Hence, the distance of the foot of the ladder from the wall is 9 m.