A ladder 10 m long reaches a window 8 m above the ground. Find the distance of the foot of the ladder from base of the wall.

Let OA is well and AB is ladder in the figure.
In triangle AOB, by pythagoras theorem
AB² = AO² + OB²
⇒ 10² = 8² + BO²
⇒ 100 = 64 + BO²
⇒ BO² = 36
⇒ BO = 6m
Hence, the distance of the root of the ladder from the base of the wall is 6 m.