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Question
A ladder 25m long reaches a window of a building 20m above the ground. Determine the distance of the foot of the ladder from the building.
Solution
Let AC be the ladder and A be the position of the window.
Then, AC = 25m, AB = 20m
Using Pythagoras theorem,
AC2 = AB2 + BC2
⇒ (25m)2 = (20m)2 + BC2
⇒ BC2 = 625m2 - 400m2
BC2 = 225m2
BC2 = (15m)2
⇒ BC = 15m
Thus, the distance of the foot of the ladder from the building is 15m.
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