document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=998935>Question 998935</A>: <I><SPAN STYLE=\"word-break: break-all;\"> prove 2/(1+cos 2 t)= sec^2t </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #616690 by </B><A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><B>josgarithmetic(39623)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><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=616690\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Find, or derive, the double angle cosine formulas, and pick the one which uses only <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%28t%29 ALIGN=MIDDLE  ALT=\"cos%28t%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >.  This is the one:  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%282t%29=2%2Acos%5E2%28t%29-1 ALIGN=MIDDLE  ALT=\"cos%282t%29=2%2Acos%5E2%28t%29-1\"   DISABLED_style= \"max-width:90%; height:auto;\" >.\r<BR>\n" );
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document.write( "LeftHandSide\r<BR>\n" );
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document.write( "and according to definition<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sec%5E2%28t%29 ALIGN=MIDDLE  ALT=\"sec%5E2%28t%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
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