document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=864223>Question 864223</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Cos2A=cosA find values of A in 0<A<360 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #520974 by </B><A HREF=/tutors/aboutme.mpl?userid=hamsanash1981@gmail.com><B>hamsanash1981@gmail.com(151)</B></A><img src=\"/images/stars/stars-09.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=hamsanash1981@gmail.com><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=520974\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> cos2A = cosA<BR>\n" );
document.write( "2cos^2A -1 = cosA   Since cos2A = 2cos^2A-1<BR>\n" );
document.write( "2cos^2A - 1 - cosA = 0<BR>\n" );
document.write( "Let x = cosA<BR>\n" );
document.write( "then <BR>\n" );
document.write( "2x^2 -x - 1 = 0<BR>\n" );
document.write( "2x^2 -2x +1x -1 = 0<BR>\n" );
document.write( "2x(x- 1) +1 (x -1) = 0<BR>\n" );
document.write( "(2x + 1) (x-1) = 0<BR>\n" );
document.write( "2x +1 = 0 x-1 =0<BR>\n" );
document.write( "2cosA= -1,  cosA = 1<BR>\n" );
document.write( "cosA = -1/2, cosA = cos0<BR>\n" );
document.write( "cosA = - (cos 60), A = 0<BR>\n" );
document.write( "- value lies on second quadrant hence A = 180 - 60<BR>\n" );
document.write( "A = 120<BR>\n" );
document.write( "therefore the values of A are 0, 120.<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );