document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=945484>Question 945484</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find the exact value of cosine 2 theta given sine of theta = negative 3 over 8 and theta is between 270 degrees and 360 degrees. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #576759 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=576759\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Find the exact value of cosine 2 theta given sine of theta = negative 3 over 8 and theta is between 270 degrees and 360 degrees.<BR>\n" );
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document.write( "Identity: cos(2x)=1-2sin^2(x)\r<BR>\n" );
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document.write( "sinx=(-3/8)<BR>\n" );
document.write( "sin^2(x)=9/64<BR>\n" );
document.write( "cos(2x)=1-2(9/64)=1-18/64=46/64<BR>\n" );
document.write( "..<BR>\n" );
document.write( "Check:<BR>\n" );
document.write( "sinx=-3/8 (Q4)<BR>\n" );
document.write( "x&#8776;337.97<BR>\n" );
document.write( "2x&#8776;675.95&#730;<BR>\n" );
document.write( "cos(2x)=cos(675.95&#730;)&#8776;0.7187..<BR>\n" );
document.write( "exact value as computed=46/64&#8776;0.7187.. </SPAN>\n" );
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