document.write( "Question 1051954: usa a sum or difference identity to find the exact value of the expression cos(5pi/12) \n" ); document.write( "

Algebra.Com's Answer #667393 by Edwin McCravy(20055) $\"\"$ $\"About$

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document.write( " is not a special angle.  We see if we \r\n" );
document.write( "can break  into a sum or difference of \r\n" );
document.write( "the three special angles , , \r\n" );
document.write( "and .\r\n" );
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document.write( "We change the special angles so as to have denominator 12:\r\n" );
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document.write( ", , \r\n" );
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document.write( "So we see that \r\n" );
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document.write( "We use the identity: \r\n" );
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document.write( "Edwin

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