The angle of elevation of the top of a building CD from the foot of the tower AB is 30 degrees and the angle of elevation of the top of the tower from the foot of the building is 60 degrees .If the tower is 50 m high. Find the height of the building. ( (Take √3 = 1.73 )

In triangle ABC

Cot 60 degrees  = BC/AB = Adjacent Side/opposite side. 

1/√3 = BC/50 .

50 = BC (√3 ) .

50/√3 = BC .

In triangle BCD

Tan 30 degrees  = DC/BC = Opposite side / Adjacent side. 

1/√3 = DC/ (50/√3 )

1/√3 = DC (√3/50 )

 50 = DC ( 3 )

DC = 50/3

DC = 16.7 m

The height of the building is 16.7 metres.