document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=927209>Question 927209</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Prove:<BR>\n" );
document.write( "Cos^4(x) - Sin^4(x) = 1 - 2Sin^2(x)<BR>\n" );
document.write( "Thank you  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #562869 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=562869\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Prove:<BR>\n" );
document.write( " Cos^4(x) - Sin^4(x) = 1 - 2Sin^2(x)<BR>\n" );
document.write( " ------<BR>\n" );
document.write( "(cos^2)^2 - (sin^2)^2 = 1 - 2sin^2<BR>\n" );
document.write( "-------<BR>\n" );
document.write( "(1-sin^2)^2 - (sin^2)^2 + 2sin^2 = 1<BR>\n" );
document.write( "------<BR>\n" );
document.write( "1 - 2sin^2 + sin^4 -sin^4 + 2sin^2 = 1<BR>\n" );
document.write( "-----<BR>\n" );
document.write( "1 = 1<BR>\n" );
document.write( "------<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "-------------- </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );