On a horizontal plane there is a vertical tower with a flag pole on the top of the tower. At a point 9 metres away from the foot of the tower the angle of elevation of the top and bottom of the flag pole are 60° and 30° respectively. Find the height of the tower and the flag pole mounted on it.
Let the height of the Flag-pole = h(m)
And height of tower = 
(m)
In ∆ABC,
tan 60° = 
√3 = 
h+
= 9√3 -------(1)
In ∆DBC,
tan 30° = 
= 
√3 
= 9
⇒ 
-------(2)
Now substituting value of 
in eqn. (1)
h+3√3 = 9√3
h = 9√3-3√3
h = 6√3 m.
Therefore height of tower is 3√3 m. and height of flag pole is 6√3 m.
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