document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=928604>Question 928604</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Prove 1-tan^2 x/2 = 2cosx/ 1+ cosx </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #563864 by </B><A HREF=/tutors/aboutme.mpl?userid=lwsshak3><B>lwsshak3(11628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=lwsshak3><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=563864\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Prove 1-tan^2 x/2 = 2cosx/ 1+ cosx<BR>\n" );
document.write( "start with left side:<BR>\n" );
document.write( "Identity: tan(x/2)=sinx/(1+cosx)<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1-tan%5E2%28x%2F2%29=1-%28%28sinx%29%2F%281%2Bcosx%29%29%5E2%0D%0A=1-%28%28sin%5E2%28x%29%29%2F%281%2Bcosx%29%5E2%29%0D%0A=1-%28%281-cosx%29%2F%281%2Bcosx%29%29=%281%2Bcosx-1%2Bcosx%29%2F%281%2Bcosx%29=2cosx%2F%281%2Bcosx%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "verified: left side=right side </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );