Question
At a point A, 20 metres above the level of water in a lake, the angle of elevation of a cloud is 30°. The angle of depression of the reflection of the cloud in the lake, at A is 60°. Find the distance of the cloud from A.
Solution
Let BE be the surface of the lake. Suppose C be the position of the cloud and C' be its reflection in the lake.
Then, AB = 20 m
Let CD = x m. Then,
CE =C'E = ( x + 20)
In ΔACD,
