document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=477025>Question 477025</A>: <I><SPAN STYLE=\"word-break: break-all;\"> prove the identity: (1-tan'squared'a)/(1+tan'squared'a)= cos'squared'a-sin'squared'a </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #327035 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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=327035\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> prove the identity: (1-tan'squared'a)/(1+tan'squared'a)= cos'squared'a-sin'squared'a<BR>\n" );
document.write( "-------------------<BR>\n" );
document.write( "(1-tan^2(a))/(1+tan^2(a))<BR>\n" );
document.write( "----<BR>\n" );
document.write( "(1-(sin/cos)^2)/(1+sin/cos)^2)<BR>\n" );
document.write( "----<BR>\n" );
document.write( "[(cos^2-sin^2)/cos^2)]/[(cos^2+sin^2)/cos^2)]<BR>\n" );
document.write( "-----<BR>\n" );
document.write( "Invert the denominator and multiply to get:<BR>\n" );
document.write( "[(cos^2-sin^2)/cos^2)]/[cos^2/(cos^2+sin^2)]<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Cancel the cos^2 factors and convert cos^2+sin^2 to 1 to get:<BR>\n" );
document.write( "---<BR>\n" );
document.write( "= cos^2-sin^2<BR>\n" );
document.write( "Which is the right side of your original problem.<BR>\n" );
document.write( "====================<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "==============<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );