SOLUTION: cos 225 as function of a positve acute angle less than 45. The reference angel of cos 225 is -cos 45 but that is not less than 45 nor is it positve.

Question 56419: cos 225 as function of a positve acute angle less than 45.
The reference angel of cos 225 is -cos 45 but that is not less than 45 nor is it positve.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
cos 225 as function of a positve acute angle less than 45.
The reference angel of cos 225 is -cos 45 but that is not less than 45 nor is it positve.
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The reference angle for 225 degrees is 225-180 or 45 degrees.
But the cos 225 is negative.
So you use the positive reference angle to find cos 45, then
you put a negative on the result because cos225 is negative.
So cos225 = -cos45 = -(sqrt2)/2 or -1/sqrt2
Cheers,
Stan H
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