document.write( "Question 1020984: Verify this trigonometric identity\r
\n" ); document.write( "\n" ); document.write( "Sin(a+b)sin(a-b)=cos^2(b)-cos^2(a) \n" ); document.write( "
Algebra.Com's Answer #636825 by robertb(5830)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "= \r
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\n" ); document.write( "\n" ); document.write( "=\"cos%5E2%28b%29+-+cos%5E2%28a%29\" \n" ); document.write( "
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