document.write( "Question 659678: How do I verify the identity of
\n" ); document.write( "(1 + sin(y))[1 + sin(-y)] = cos^2(y) \n" ); document.write( "

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How do I verify the identity of
\n" ); document.write( "(1 + sin(y))[1 + sin(-y)] = cos^2(y)
\n" ); document.write( "start with left side:
\n" ); document.write( "(1 + sin(y))[1 + sin(-y)]
\n" ); document.write( "Identity: sin(-y)=-sin(y)
\n" ); document.write( "(1 + sin(y))[1 - sin(y)]
\n" ); document.write( "difference of 2 squares
\n" ); document.write( "=1-sin^2(y)
\n" ); document.write( "=cos^2(y)
\n" ); document.write( "verified: left side=right side
\n" ); document.write( " \n" ); document.write( "

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