document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1131550>Question 1131550</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Establish the following identity:<BR>\n" );
document.write( "cos(A+B)cos(A-B)=cos^2(A)+cos^2(B)-1 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #748223 by </B><A HREF=/tutors/aboutme.mpl?userid=MathLover1><B>MathLover1(20850)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=MathLover1><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=MathLover1><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=748223\">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=cos%28A%2BB%29cos%28A-B%29=cos%5E2%28A%29%2Bcos%5E2%28B%29-1+ ALIGN=MIDDLE  ALT=\"cos%28A%2BB%29cos%28A-B%29=cos%5E2%28A%29%2Bcos%5E2%28B%29-1+\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "start with left side:\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28cos%28A%29+cos%28B%29+-+sin%28A%29+sin%28B%29%29%28sin%28A%29+sin%28B%29+%2B+cos%28A%29+cos%28B%29%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%28A%29%2Acos%28B%29%2Asin%28A%29%2Asin%28B%29%2Bcos%5E2%28A%29%2A+cos%5E2%28B%29+-+sin%5E2%28A%29+%2Asin%5E2%28B%29-+sin%28A%29%2A+sin%28B%29%2Acos%28A%29%2Acos%28B%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cross%28cos%28A%29+cos%28B%29sin%28A%29+sin%28B%29%29%2Bcos%5E2%28A%29+cos%5E2%28B%29+-+sin%5E2%28A%29+sin%5E2%28B%29+-+cross%28sin%28A%29+sin%28B%29cos%28A%29+cos%28B%29%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%5E2%28A%29+cos%5E2%28B%29+-+sin%5E2%28A%29+sin%5E2%28B%29%29 ALIGN=MIDDLE  ALT=\"cos%5E2%28A%29+cos%5E2%28B%29+-+sin%5E2%28A%29+sin%5E2%28B%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >..............since <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sin%5E2%28A%29=1-cos%5E2%28A%29 ALIGN=MIDDLE  ALT=\"sin%5E2%28A%29=1-cos%5E2%28A%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > and <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sin%5E2%28B%29=1-cos%5E2%28B%29 ALIGN=MIDDLE  ALT=\"sin%5E2%28B%29=1-cos%5E2%28B%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >, we have\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%5E2%28A%29+cos%5E2%28B%29+-+%281-cos%5E2%28A%29%29+%281-cos%5E2%28B%29%29 ALIGN=MIDDLE  ALT=\"cos%5E2%28A%29+cos%5E2%28B%29+-+%281-cos%5E2%28A%29%29+%281-cos%5E2%28B%29%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%5E2%28A%29+cos%5E2%28B%29+-++%281-cos%5E2%28B%29-cos%5E2%28A%29%2Bcos%5E2%28A%29cos%5E2%28B%29%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%5E2%28A%29+cos%5E2%28B%29+-++1%2Bcos%5E2%28B%29%2Bcos%5E2%28A%29-cos%5E2%28A%29cos%5E2%28B%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cross%28cos%5E2%28A%29+cos%5E2%28B%29%29+-++1%2Bcos%5E2%28B%29%2Bcos%5E2%28A%29-cross%28cos%5E2%28A%29cos%5E2%28B%29%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=+-++1%2Bcos%5E2%28B%29%2Bcos%5E2%28A%29 ALIGN=MIDDLE  ALT=\"+-++1%2Bcos%5E2%28B%29%2Bcos%5E2%28A%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > rearrange the terms\r<BR>\n" );
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document.write( "=<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%5E2%28A%29%2Bcos%5E2%28B%29-++1+ ALIGN=MIDDLE  ALT=\"cos%5E2%28A%29%2Bcos%5E2%28B%29-++1+\"   DISABLED_style= \"max-width:90%; height:auto;\" >-> identity is proven\r<BR>\n" );
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document.write( " </SPAN>\n" );
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