The angles of elevation of the top of a tower 72 metre high from the top and bottom of a building are 30° and 60° respectively. What is the height (in metres) of building?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4, i.e. 48
Let the height of the building = x meter
In △ABC
tan 60° = AB/BC
BC = 72/√3 = 24√3 = DE
In △ADE
tan 30° = 72-x/24√3
1/√3 = 72-x/24√3
x = 48 m