Q21 of 28 Page 93

From a point A 20m high above the water level in a lake the angle of elevation of a cloud is 30°. If the angle of depression of the reflection of the cloud in the lake from point A is 60° then find the distance of the cloud from the point A.


Let Height of the Cloud is g from the surface of the lake and CE = g.


Given angle of elevation of the cloud ∠CED = 30o, Angle of Depression of the reflection of the Cloud is ∠EDF = 60o. AC = AF (reflections)(It doesn’t seem in the image.)


in DEF,



………….(1)


in CDE,



DE = CE√3…………(2)




20 + g = 3g – 60


80 = 2g


g = 40


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