SOLUTION: Find the exact value by using a half-angle identity. (4 points) cos(5pi/12) Here is my work, can someone please check to see if I did it right? cos ((5 pi/6)/2) = +/- sqrt(

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Question 979506: Find the exact value by using a half-angle identity. (4 points)
cos(5pi/12)
Here is my work, can someone please check to see if I did it right?
cos ((5 pi/6)/2) = +/- sqrt( (1+cos (5 pi/6))/2 )
cos(5 pi/6) = -sqrt(3)/2
cos (5 pi/12) = +/- sqrt( (2/2-sqrt(3)/2)/2 )
cos (5 pi/12) = +/- sqrt( ((2-sqrt(3))/2)/2 )
cos (5 pi/12) = sqrt( ( (2-sqrt(3))/4 ) )

Answer by ikleyn(52799)   (Show Source): You can put this solution on YOUR website!

Find the exact value by using a half-angle identity. (4 points)
.

Here is my work, can someone please check to see if I did it right?

= +/-     correct

=                                       correct

= +/-                       correct

= +/-                   correct

=                               correct


EVERYTHING IS CORRECT.
==========================

You can write the last expression as

= .


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