The angle at which the man should observe is 45 degrees.
Given :
height of man = 1.5m
height of tower = 81.5 m
distance between tower and man = 80 m
Since, ABCD is a rectangle, AD = BC = 80m
Similarly, AB = CD = 1.5m
EC = ED + CD
81.5 = ED + 1.5
ED = 80m
Now, in order to find the angle EAD, we use trigonometric functions,
tan ∅ = perpendicular / base = ED / AD
tan ∅ = 80 /80 = 1
∅ = [tex]tan^{-1} (1)[/tex]
∅ = 45°.
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