The angle of elevation of the top of a tower from a point on the same level as the foot of the tower is 30 degree. On advancing 150m towards the foot of the tower, the angle of elevation becomes 60 degree. Find the height of the tower.

We can plot the following diagram from the given data as-

Use trigonometric ratios in the triangle ABD,

 ......(1)

Similarly using trigonometric ratios in the triangle ABC, we get,

 ......(2) 

Use equation(1) in equation (2),

 ......(3)

Put the value of a in equation(1) to get the value of h,

Therefore the height of the tower is 129.9 m.

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