maths
posted by Shane .
A tourist viewing Sydney Harbour from a building 180 metres above sea level observes a ferry which is 850 metres from the base of the building.Find the angle of depression of his line of sight.

We draw and solve a rt. triangle:
Y = 180 m. = Ht.
X = 850 m = Hor..Distance of ferry.
Z = Hyp. = Line of sight.
tanA = Y/X = 180/850 = 0.21176.
A = 12o = Angle of depression.