Find the height of a tree when it is found that on walking away from it 20 metres, in horizontal line through its base, the elevation of its top changes from 60 degree to 30 degree.

Question

Find the height of a tree when it is found that on walking away from it 20 metres, in horizontal line through its base, the elevation of  its top changes from 60 degree to 30 degree.

drwls · Answer

Let the height be H.
Let the (closer) distance for which the elevation is 60 degrees be D.

H/D = tan 60 = sqrt3 = 1.732
H/(D+20) = tan30 = 1/sqrt3= 0.5774

(D+20)/D = 3
1 + 20/D = 3
20/D = 2
D = 10 m, exactly
H = sqrt3*10 = 17.32 m

Prateeksha · Answer

Can u please do the sum much clearly