document.write( "Question 818520: verify the identity by simplifying the left side
\n" ); document.write( "sin^2x-sin^2y=cos^2y-cos^2x \n" ); document.write( "
Algebra.Com's Answer #492610 by jhunjiro(67)\"\" \"About 
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\n" ); document.write( "Given
\n" ); document.write( "sin^2x-sin^2y=cos^2y-cos^2x\r
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\n" ); document.write( "Pythagorean Identity
\n" ); document.write( " cos^2x + sin^2y = 1
\n" ); document.write( " sin^2Ø = 1 - cos^2Ø
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\n" ); document.write( " sin^2x-sin^2y=cos^2y-cos^2x
\n" ); document.write( " (1-cos^2x)-(1 - cos^2y)=cos^2y-cos^2x
\n" ); document.write( " 1 -cos^2x -1 + cos^2y =cos^2y-cos^2x
\n" ); document.write( " 1 -1 -cos^2x + cos^2y =cos^2y-cos^2x
\n" ); document.write( " -cos^2x + cos^2y =cos^2y-cos^2x\r
\n" ); document.write( "\n" ); document.write( " cos^2y - cos^2x =cos^2y-cos^2x
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