document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=679413>Question 679413</A>: <I><SPAN STYLE=\"word-break: break-all;\"> verify the identity\r<BR>\n" );
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document.write( "cos2x=(cot^2 x-1)/cot^2 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 #421957 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=421957\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> verify the identity <BR>\n" );
document.write( "cos2x=(cot^2 x-1)/cot^2 x+1<BR>\n" );
document.write( "start with right side<BR>\n" );
document.write( "(cot^2x-1)/cot^2x+1<BR>\n" );
document.write( "[(cos^2x/sin^2x)-1]/[(cos^2x/sin^2x)+1]<BR>\n" );
document.write( "=[(cos^2x-sin^2x)/sin^2x]/[(cos^2x+sin^2x)/sin^2x]<BR>\n" );
document.write( "sin^2x cancels out<BR>\n" );
document.write( "=[(cos^2x-sin^2x)/[(cos^2x+sin^2x)]<BR>\n" );
document.write( "=[(cos^2x-sin^2x)/1<BR>\n" );
document.write( "=cos2x<BR>\n" );
document.write( "verified: right side=left side </SPAN>\n" );
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