document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=808770>Question 808770</A>: <I><SPAN STYLE=\"word-break: break-all;\"> for the interval of 0-2(pi) solve the equation <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=for+the+interval+of+0-2%28pi%29+solve+the+equation+ ALIGN=MIDDLE  ALT=\"for+the+interval+of+0-2%28pi%29+solve+the+equation+\"   DISABLED_style= \"max-width:90%; height:auto;\" >cos4xcos2x+sin4xsin2x=sqrt(3)/2 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #487189 by </B><A HREF=/tutors/aboutme.mpl?userid=DrBeeee><B>DrBeeee(684)</B></A><img src=\"/images/stars/stars-11.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=DrBeeee><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=487189\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Given:<BR>\n" );
document.write( "(1) cos(4x)cos(2x) + sin(4x)sin(2x) = sqrt(3)/2<BR>\n" );
document.write( "Use the difference formula<BR>\n" );
document.write( "(2) cos(a-b) = cos(a)cos(b) + sin(a)sin(b) to obtain<BR>\n" );
document.write( "(3) cos(4x - 2x) = cos(4x)cos(2x) + sin(4x)sin(2x)<BR>\n" );
document.write( "Now equate (1) and (3) to get<BR>\n" );
document.write( "(4) cos(4x - 2x) = sqrt(3)/2 or<BR>\n" );
document.write( "(5) cos(2x) = sqrt(3)/2<BR>\n" );
document.write( "Use your calculator to evaluate<BR>\n" );
document.write( "(6) 2x = arccos(sqrt(3)/2) and get<BR>\n" );
document.write( "(7) 2x = 30 or<BR>\n" );
document.write( "(8) x = 15 degrees<BR>\n" );
document.write( "This is also the solution at <BR>\n" );
document.write( "(9) x = 15+180 or<BR>\n" );
document.write( "(10) x = 195 degrees<BR>\n" );
document.write( "Answer: x = {15,195} degrees </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );