document.write( "Question 1159430: Prove sin^2 x cos^2 x + cos^4 x = (1-sinx) (1+sinx) is an identity. I need steps please \n" ); document.write( "

Algebra.Com's Answer #782453 by Boreal(15235) $\"\"$ $\"About$

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sin^2 x cos^2 x + cos^4 x = (1-sinx) (1+sinx)=(1-sin^2x)=cos^2x\r
\n" ); document.write( "\n" ); document.write( "left side factor out a cos^2x and get cos^2x(sin^2x+cos^2x)
\n" ); document.write( "but sin^2x+cos^2x=1
\n" ); document.write( "so cos^2 x (1)=cos^2 x\r
\n" ); document.write( "\n" ); document.write( "the key identities are cos^2x+sin^2 x=1
\n" ); document.write( "and 1-sin^2x=cos^2 x
\n" ); document.write( "and 1-cos^2 x= sin^2 x\r
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