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Question
A ladder 15 metres long reaches a window which is 9 metres above the ground on one side of a street. Keeping its foot at the same point, the ladder is turned to other side of the street to reach a window 12 metres high. The width of the street is:
A ladder 15 metres long reaches a window which is 9 metres above the ground on one side of a street. Keeping its foot at the same point, the ladder is turned to other side of the street to reach a window 12 metres high. The width of the street is:
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Solution
The correct option is C 21 metres
Ladder makes a right angled triangle with window, where length of ladder is hypotenuse and height of window is perpendicular of the triangle.
⇒ Width of the street = Sum of bases/projection of ladder on road in both cases =√(15)2−(9)2+√(15)2−(12)2
=12+9 =21 metres
Ladder makes a right angled triangle with window, where length of ladder is hypotenuse and height of window is perpendicular of the triangle.
=√(15)2−(9)2+√(15)2−(12)2
=12+9
=21 metres
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