document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1106830>Question 1106830</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Verify the identity. Please help\r<BR>\n" );
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document.write( "cos 4u = cos^2 2u - sin^2 2u </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #721811 by </B><A HREF=/tutors/aboutme.mpl?userid=greenestamps><B>greenestamps(13203)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=greenestamps><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=greenestamps><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=721811\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <br><BR>\n" );
document.write( "This one doesn't involve any manipulation of the expressions -- just a change in variable.<br><BR>\n" );
document.write( "cos(2x) = (cos(x))^2 - (sin(x))^2<br><BR>\n" );
document.write( "so<br><BR>\n" );
document.write( "cos(4u) = (cos(2u))^2-sin(2u))^2. </SPAN>\n" );
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