Question

From a point on the ground, the angles of elevation of the bottom and the top of a transmission tower fixed at the top of a 20 m high building are 45° and 60° respectively. Find the height of the tower

Answer 1

Take tan45(1) - you will get the base as 20 m 
Then take tan60 - and you will get the height as 20* root 3 

Answer 2

let AB=tower BC =building dc = distance from point
take tan45= 1=20/dc so,. dc= 20m
tan 60= √3=. 20+AB/20
20√3-20=AB
AB=20(√3-1)