document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=177042>Question 177042</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Prove the following identity: -sin^2x-sin^2y+1=cos(x+y)cos(x-y) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #132366 by </B><A HREF=/tutors/aboutme.mpl?userid=Edwin+McCravy><B>Edwin McCravy(20056)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Edwin+McCravy><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=Edwin+McCravy><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=132366\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=matrix%287%2C3%2C%0D%0A%0D%0A-Sin%5E2x-Sin%5E2y%2B1%2C%22=%22%2CCos%28x%2By%29Cos%28x-y%29%2C%0D%0A++++++++++++++%22%22%2C%22=%22%2C%28Cos%28x%29Cox%28y%29-Sin%28x%29Sin%28y%29%29%28Cos%28x%29Cox%28y%29%2BSin%28x%29Sin%28y%29%29%2C%0D%0A++++++++++++++%22%22%2C%22=%22%2CCos%5E2x%2ACos%5E2y-Sin%5E2x%2ASin%5E2y%2C%0D%0A++++++++++++++%22%22%2C%22=%22%2C%281-Sin%5E2x%29%281-Sin%5E2y%29-Sin%5E2x%2ASin%5E2y%2C%0D%0A++++++++++++++%22%22%2C%22=%22%2C1-Sin%5E2y-Sin%5E2x%2BSin%5E2x%2ASin%5E2y-Sin%5E2x%2ASin%5E2y%2C%0D%0A++++++++++++++%22%22%2C%22=%22%2C1-Sin%5E2y-Sin%5E2x%2C%0D%0A++++++++++++++%22%22%2C%22=%22%2C-Sin%5E2x-Sin%5E2y%2B1%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" > <BR>\n" );
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