document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=711650>Question 711650</A>: <I><SPAN STYLE=\"word-break: break-all;\"> (cos^4(x)-sin^4(x))/cos^2(x) = 1-tan^2(x)\r<BR>\n" );
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document.write( "I need the proof, PLEASE </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #437539 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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/cgi-bin/show-face.mpl?user=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=437539\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> (cos^4(x)-sin^4(x))/cos^2(x) = 1-tan^2(x)<BR>\n" );
document.write( "Multiply by cos^2<BR>\n" );
document.write( "(cos^4(x)-sin^4(x)) = cos^2 - sin^2<BR>\n" );
document.write( "(cos^2(x)-sin^2(x))*(cos^2 + sin^2) = cos^2 - sin^2<BR>\n" );
document.write( "(cos^2(x)-sin^2(x))*1 = cos^2 - sin^2<BR>\n" );
document.write( "----------------------<BR>\n" );
document.write( "The way to do these is to try things.<BR>\n" );
document.write( " </SPAN>\n" );
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