Let C be the Position of the Cloud

A-B Line Represents the Line which is 'h' metres above the Lake.

A is the Point from which the Cloud is Observed and θ is the Angle of Elevation of the Cloud viewed from Point A

C'' is the Reflection of the Cloud seen from Point A

α is the Angle of Depression of the Cloud reflection viewed from Point A

LK is the Surface of the Lake

z is the Height of the Cloud from the Point where it is Viewed (i.e.) AB Line.

From the Figure :

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In the Similar way :

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Equating Both 'AB's

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⇒ z × Tanα = 2h × Tanθ + z × Tanθ

⇒ z(Tanα - Tanθ) = 2hTanθ

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But the Height of the Cloud above the Lake is z + h

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