From a point on the ground, the angles of elevation of the bottom and top of a transmission tower fixed at the top of a 10 m high building are 30o and 60o respectively. Find the height of the tower.
Let the point on the ground be A.
Let BC be the height of the building, BC=10m
And CD be the height of the transmission tower, CD=y m(let)
In ΔABC,
AB=10√3m………………………….(1)
In Δ ABD,
(From eq (1) AB=10√3)
10 + y=10 × 3
10 + y=30
y=20m
∴ The height of tramisiion tower =20m.