document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=873157>Question 873157</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If cos x=4/5 and x is an acute angle, find the exact value of cos2x, in simplest fractional form  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #526668 by </B><A HREF=/tutors/aboutme.mpl?userid=mananth><B>mananth(16946)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mananth><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=mananth><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=526668\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> cos(2x) = 2 cos^2x - 1  \r<BR>\n" );
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document.write( "cos x = 4/5\r<BR>\n" );
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document.write( "cos^2x = 16/25\r<BR>\n" );
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document.write( "2*cos^2x= 32/25\r<BR>\n" );
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document.write( "2*cos^2x-1= 32/25  -1\r<BR>\n" );
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document.write( "=7/25\r<BR>\n" );
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document.write( "cos(2x)= 7/25\r<BR>\n" );
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