trig
posted by Arun .
The angle of depression of the top and bottom of a tower as seen from the top of a 100m high cliff are 30degree and 60degree respectively. find the height of the tower

I assume you made a sketch.
On mine I let the distance between tower and cliff be x m
then tan60° = 100/x
x = 100/tan60°
In my smaller rightangled triangle at the top of my diagram ,
let the difference between height of tower and height of cliff be h
then tan 30 = h/x
h = xtan30
= (100/tan60)tan30
then height of tower = 100  h
I will let you do all that buttonpushing,
let me know what you got 
99.99