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A person is standing in a room of width 200 cm. A plane mirror of vertical length 10 cm is fixed on awall in front of the person. The person looks intothe mirror from distance 50 cm. How much width(height) of the wall behind him will he be able tosee:(A) 30 cm(C) 50 cm(B) 40 cm(D) none of these |
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Answer» (C) 50 cmExplanation:WIDTH of the room = 200CM (Given)Length of plane mirror = 10cm (Given)Distance of the person looking into mirror = 50cm (Given)In first triangle - TanФ = x/200 --- 1In second triangle - TanФ = 5/50 --- 2Equating both the equations - 5/50 = x/200x = 20cmThus, the height of the wall is 2x+10 = 50The width of the wall he will be able to SEE = 50cm |
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