posted by john .
From a point A is 8.20 meters above level ground,the angle of elevation of the top of a building is 31degrees 20 min and the angle of depression of the base of the building is 12degree 50 min. Approximate the heighth of the building
If the distance of A is d, and the building's height is h,
(h-8.2)/d = tan 31°20'
8.2/d = tan 12°50'
so, equating d,
(h-8.2)/tan 31°20' = 8.2/tan 12°50'
(h-8.2)/.6088 = 8.2/.2278
h = 30.11 m