document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1145897>Question 1145897</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Show that cos18° = [sqrt(10 + 2sqrt5)]/4 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #767300 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=767300\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Show that cos18° = [sqrt(10 + 2sqrt5)]/4<BR>\n" );
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document.write( "Use the sin(18)<BR>\n" );
document.write( "Then, cos(18) = sqrt(1 -sin^2(18))<BR>\n" );
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document.write( "Or, sin(18) = 2sin(9)*cos(9)\r<BR>\n" );
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