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Question:

Two vertical poles 20 m and 80 m high stand 50 m apart on a horizontal plane. The height of the point of intersection of the lines joining the top of each pole to the foot of the other is 15 m, 16 m, 18 m, 50 m?

16 m

50 m

15 m

18 m

Solution:

From figure ,The projection of the intersection point divides the base line in the ration1:4SoBD=10andDE=40InΔABEtanE=25⋯(1)InΔCDEtanE=CD40⋯(2)From(1)(2)⟹CD=16