A ladder is placed in such a way that its foot is at a distance of 15 m from a wall and its top reaches a window 20 m above the ground. Find the length of the ladder.
Ladder AB and distance from the window BC = 20 m.
AC is the distance of the ladder from the building = 15 m.
From the figure, ΔABC is a right triangle.
In a right angled triangle
(Hypotenuse) 2 = (Base)2 + (Height)2
where hypotenuse is the longest side.
(AB)2 = (AC)2 + (BC)2
⇒AB2 = (20) 2 + (15) 2
⇒ AB2 = 400 + 225 = 625
⇒AB = 25 m
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