<PRE><B>Question 211679</B>
find the exact value of the following without using a calculator: 
(sin^2)(225degrees)-(cos^2)(300degrees)
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The reference angle for 225 degrees is 45 degrees in the 3rd quadrant
sin(225) = -sin(45) = (sqrt(2))/2
So, sin^2(225) = 2/4 = 1/2
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The reference angle for 300 degrees is 60 degrees in the 4th quadrant.
cos(300) = cos(60) = 1/2
So, cos^2(300) = (1/2)^2 = 1/4
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Ans: 1/2 - 1/4 = 1/4
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Cheers,
Stan H.</PRE>