document.write( "Question 136157: cos^2xcos^2y+sin^2xsin^2y+sin^2xcos^2y+sin^2ycos^2x=1 \n" ); document.write( "

Algebra.Com's Answer #99709 by vleith(2983) $\"\"$ $\"About$

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Given: cos^2xcos^2y+sin^2xsin^2y+sin^2xcos^2y+sin^2ycos^2x=1
\n" ); document.write( "We know that cos^2x + sin^2x = 1\r
\n" ); document.write( "\n" ); document.write( "cos^2xcos^2y+sin^2xsin^2y+sin^2xcos^2y+sin^2ycos^2x=1
\n" ); document.write( "cos^2xcos^2y+sin^2xcos^2y+sin^2xsin^2y+sin^2ycos^2x=1
\n" ); document.write( "(cos^2x + sin^2x)cos^2y+(sin^2x +cos^2x)sin^2y=1
\n" ); document.write( "(1)cos^2y+(1)sin^2y=1
\n" ); document.write( "cos^2y + sin^2y = 1
\n" ); document.write( "1 = 1 True!\r
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