# The angle of elevation of the top of a tower standing on a horizontal plane from a point C is α. After walking a distance d towards the foot of the tower the angle of elevation is found to be β. The height of the tower isA. B. C. D.

Given: The angle of elevation of the top of a tower standing on a horizontal plane from a point C is α. After walking a distance d towards the foot of the tower the angle of elevation is found to be β.

To find: The height of the tower

Solution:

Let h be the height of the tower on horizontal plane.

Let α be the angle of elevation from point C and β be the angle of elevation from point B

Given CB = d

In Δ PCB

tan (α) =

x =

In Δ CDB

tan(β) =

⇒ tanβ ( h - d tanα) = h tanα

⇒  h tanβ - d tan a tanβ = h tan a

⇒  h (tanβ – tan a) = d tan a tanβ

Use the formula:

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