document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=86725>Question 86725</A>: <I><SPAN STYLE=\"word-break: break-all;\"> please help me solve this equation  sin 2x-cosx=0 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #62748 by </B><A HREF=/tutors/aboutme.mpl?userid=longjonsilver><B>longjonsilver(2297)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=longjonsilver><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=longjonsilver><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=62748\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> need to get rid of either the sin or cos... to make an equation in just one \"variable\". The obvious one is the sin 2x since there is a formula:<BR>\n" );
document.write( "sin2x = 2sinx cosx\r<BR>\n" );
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document.write( "so, 2sinXcosX - cosX = 0\r<BR>\n" );
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document.write( "looking at this, we have a cosX in both terms so we can factorise.... solving any equation we are always looking to factorise:\r<BR>\n" );
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document.write( "cosX(2sinX-1) = 0\r<BR>\n" );
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document.write( "which means that either<BR>\n" );
document.write( "cosX=0 or 2sinX-1 = 0<BR>\n" );
document.write( "cosX=0 or 2sinX = 1<BR>\n" );
document.write( "cosX=0 or sinX = 1/2<BR>\n" );
document.write( "X=90 or X=30... in the first quadrant. There are other angles that give these answers too but you do not quote the range of angles acceptable.\r<BR>\n" );
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document.write( "hope this helps<BR>\n" );
document.write( "Jon\r<BR>\n" );
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document.write( " </SPAN>\n" );
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