document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1056970>Question 1056970</A>: <I><SPAN STYLE=\"word-break: break-all;\"> cos(2x) + cos(4x) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #672082 by </B><A HREF=/tutors/aboutme.mpl?userid=solve_for_x><B>solve_for_x(190)</B></A><img src=\"/images/stars/stars-09.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=solve_for_x><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=672082\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The formula to use for this is:\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%28a%29+%2B+cos%28b%29+=+2cos%28%28a+%2B+b%29%2F2%29cos%28%28a+-+b%29%2F2%29 ALIGN=MIDDLE  ALT=\"cos%28a%29+%2B+cos%28b%29+=+2cos%28%28a+%2B+b%29%2F2%29cos%28%28a+-+b%29%2F2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "Applying this to cos(2x) + cos(4x) gives:\r<BR>\n" );
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document.write( "Then, since cos(-x) = cos(x), we get:\r<BR>\n" );
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