document.write( "Question 388940: How do you contract: sin^2(4pi/9)-cos^2(4pi/9)? \n" ); document.write( "
Algebra.Com's Answer #275412 by stanbon(75887)\"\" \"About 
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How do you contract: sin^2(4pi/9)-cos^2(4pi/9)?
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\n" ); document.write( "In general, sin^2(x)-cos^2(x)
\n" ); document.write( "= sin^2(x)-[1-sin^2(x)]
\n" ); document.write( "= 2sin^2(x)-1
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\n" ); document.write( "Your Problem:
\n" ); document.write( "sin^2(4pi/9)-cos^2(4pi/9)
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\n" ); document.write( "= 2sin^2[4pi/9]-1
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.\r
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