document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=815262>Question 815262</A>: <I><SPAN STYLE=\"word-break: break-all;\"> prove :[cos(pi+x)cos(-x)]/[sin(pi-x)cos(pi/2+x)]=cot^2x </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #490821 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=490821\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> prove :[cos(pi+x)cos(-x)]/[sin(pi-x)cos(pi/2+x)]=cot^2x<BR>\n" );
document.write( "***<BR>\n" );
document.write( "start with left side:<BR>\n" );
document.write( "[cos(pi+x)cos(-x)]/[sin(pi-x)cos(pi/2+x)]<BR>\n" );
document.write( "=[-cos(x)cos(x)]/[sin(x)*-sin(x)]<BR>\n" );
document.write( "=-cos^2(x)/-sin^2(x)=cot^2(x)<BR>\n" );
document.write( "verified: left side=right side </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );