Q.3 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.

Here, the ladder forms a right angled triangle.
\(\therefore \) \(a^2 + 12^2 = 15^2 \)(By Pythagoras property)
Or, \(a^2+ 144 = 225\)
Or, \(a^2 = 225 – 144 \)
Or, \(a^2 = 81 \)
\(\therefore \) a = \(\sqrt{81}= 9 \) m
Thus, the distance of the foot from the ladder = 9m