document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=609772>Question 609772</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The expression cos^2 40 degrees - sin^2 40 degrees has the same value as<BR>\n" );
document.write( "(1) sin 20 degrees   (2) sin80 degrees    (3) cos 80 degrees  (4) cos 20 degrees<BR>\n" );
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document.write( "I do not know how to go about this question...all I know is this identity <BR>\n" );
document.write( "sin^2 theta + cos^2 theta = 1, but I do not know how to apply it. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #383929 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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=383929\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Use the identity cos^2(x) - sin^2(x) = cos(2x) to get\r<BR>\n" );
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document.write( "cos^2(x) - sin^2(x) = cos(2x)\r<BR>\n" );
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document.write( "cos^2(40) - sin^2(40) = cos(2*40)\r<BR>\n" );
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document.write( "cos^2(40) - sin^2(40) = <font color=\"red\">cos(80)</font>\r<BR>\n" );
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