document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=775868>Question 775868</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help me solve this equation for u: cos2u-7cosu+7=0 with [0,2pi) as a restriction. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #473221 by </B><A HREF=/tutors/aboutme.mpl?userid=lwsshak3><B>lwsshak3(11628)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=lwsshak3><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=473221\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> solve this equation for u: cos2u-7cosu+7=0 with [0,2pi) as a restriction.<BR>\n" );
document.write( "***<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%282u%29-7cosu-7=0 ALIGN=MIDDLE  ALT=\"cos%282u%29-7cosu-7=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%5E2%28u%29-sin%5E2%28u%29-7cosu-7=0 ALIGN=MIDDLE  ALT=\"cos%5E2%28u%29-sin%5E2%28u%29-7cosu-7=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%5E2%28u%29-1%2Bcos%5E2%28u%29-7cosu-7=0 ALIGN=MIDDLE  ALT=\"cos%5E2%28u%29-1%2Bcos%5E2%28u%29-7cosu-7=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2cos%5E2%28u%29-7cosu-8=0 ALIGN=MIDDLE  ALT=\"2cos%5E2%28u%29-7cosu-8=0\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "solve for cos(u) by quadratic formula:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos%28u%29+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ ALIGN=MIDDLE  ALT=\"cos%28u%29+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "a=2, b=-7, c=-8<BR>\n" );
document.write( "cos(u)&#8776;4.41(reject, (-1 < cos(u) < 1)<BR>\n" );
document.write( "or <BR>\n" );
document.write( "cos(u)&#8776;-0.9075<BR>\n" );
document.write( "u=0.4335, 3.575 (in Q3 and Q4 where cos<0)<BR>\n" );
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