<PRE><B>Question 415003</B>
On cloudy days, the sun intensity I (in calories per square centimeter) is given by I = I(max) sin^2 (pi t / D) where I(max) is the largest sun intensity and D is the number of daylight hours. If D = 12, how many hours after sunrise is intensity exactly half of the maximum level? (Assume t is in between zero and D) 
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Solve sin^2[(pi/12)t] = 1/2
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sin[(pi/12)t] = sqrt(2)/2
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(pi/12)t = pi/4
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(t/12) = 1/4
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t = 3 hrs.
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Cheers,
Stan H.

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