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A pole and its shadow have same length, ...

A pole and its shadow have same length, find the angle of the sun ray made with the earth at that time.

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We can assume that the sun rays are alomost parallel to each other. A part of these rays will be blocked by a man. This blocked region will be the shadow(Fig. 33.4).As the time passes, the Sun revolves around the Earth.We know that the sunrays are horizontal at 6 : 00 A.M and at 6 : P.M. At 10 : 00 A.M. the Sun would have gone up in the sky.

Calculation : As the Sun covers `180^(@)` in sky in 12 hours from 6 : 00 A.M to 12 : 00 P.M., it covers `15^(@)` in 1 hour. (Actually, it is the Earth that is rotating, but the effect is same as seen from the Earth) So, till 10 :00 A.M the Sun has covered
`15^(@) xx 4 = 60^(@)`.
Therefore, the lenggth of the man.s shadow will be
`l = 6 cot 60^(@) = 2 sqrt3` ft.
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