posted by Anonymous .
The angle of elevation of the bottom of a window 10 meter above the ground level from a point on the ground is 30degrees.
A pole projecting outwards and upwards from the bottom of the window makes an angle of 30 degrees with the wall.
If the angle of elevation of the top of the pole observed from the same point on the ground is 60 degrees, what is the the length of the pole?
Ah, such carefully contrived angles.
point on the ground Q
base of the wall A
bottom of the window B
top of the pole P
∆ABQ is a 30-60-90 ∆, so BQ=20
∆BPQ is also 30-60-90, so BP=20/√3
so, the pole is 20/√3 = 11.5m