document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=458198>Question 458198</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Verify the identity.<BR>\n" );
document.write( "tan^2 x/2 = sec x-1/sec x+1 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #314572 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=314572\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Verify the identity.<BR>\n" );
document.write( "tan^2 x/2 = sec x-1/sec x+1<BR>\n" );
document.write( "..<BR>\n" );
document.write( "Starting from left side<BR>\n" );
document.write( "tan^2 x/2=(1-cosx)/(1+cosx)<BR>\n" );
document.write( "=(1-cosx)/(1+cosx)<BR>\n" );
document.write( "=[(1-1/secx)/(1+1/secx)]<BR>\n" );
document.write( "=[(secx-1)/secx]/[(secx+1)/secx]<BR>\n" );
document.write( "secx cancels out<BR>\n" );
document.write( "(secx-1)/(secx+1)<BR>\n" );
document.write( "verified: left side = right side </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );