SOLUTION: Find the exact value of the expression cos(pi/12)cos(3pi/4) - sin(pi/12)sin(3pi/4) I appreciate your help!

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Question 140797: Find the exact value of the expression
cos(pi/12)cos(3pi/4) - sin(pi/12)sin(3pi/4)

I appreciate your help!

Answer by edjones(8007)   (Show Source): You can put this solution on YOUR website!
cos(pi/12)cos(3pi/4) - sin(pi/12)sin(3pi/4)
=((sqrt(3)/2)(-sqrt(2)/2))-((1/2)(sqrt(2)/2))
=-sqrt(6)/4 - sqrt(2)/4
=
=-.965926
.
Ed

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