document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=753085>Question 753085</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If cos theta = - 4/5 and 180degree < theta < 270degree, use trigonometric identities to find the exact value of sin 2theta.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #458197 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=458197\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If cos theta = - 4/5 and 180degree < theta < 270degree, use trigonometric identities to find the exact value of sin 2theta.<BR>\n" );
document.write( "**<BR>\n" );
document.write( "sin2x=2sinxcosx<BR>\n" );
document.write( "given cosx=-4/5 (in Q3 where cos and sin<0)<BR>\n" );
document.write( "sinx=-3/5 (working with 3-4-5 reference right triangle<BR>\n" );
document.write( "sin2x=2*-4/5*-3/5=24/25<BR>\n" );
document.write( "..<BR>\n" );
document.write( "check with calculator:<BR>\n" );
document.write( "cosx=-4/5 in Q3<BR>\n" );
document.write( "x&#8776;36.87º+180º&#8776;216.87º<BR>\n" );
document.write( "2x&#8776;433.74º (Q1 where sin>0)<BR>\n" );
document.write( "sin2x=sin(433.74º)&#8776;0.9600..<BR>\n" );
document.write( "exact value=24/25&#8776;0.9600..<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );