document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=934032>Question 934032</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If cos(A) = -5/13, where pi/2 is less than or equal to A < pi, then evaluate cos(A-(pi/4)) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #567181 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=567181\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If cos(A) = -5/13, where pi/2 is less than or equal to A < pi, then evaluate cos(A-(pi/4))<BR>\n" );
document.write( "***<BR>\n" );
document.write( "sin(A)=12/13 (working with a (5-12-13) reference right triangle in quadrant II)<BR>\n" );
document.write( "reference angle A is in quadrant II<BR>\n" );
document.write( "cos(x-y)=cosxcosy+sinxsiny<BR>\n" );
document.write( "cos(A-(&#960;/4))=cosAcos(&#960;/4)+sinAsin(&#960;/4)<BR>\n" );
document.write( "=-5/13*(&#8730;2/2)+12/13*&#8730;2/2<BR>\n" );
document.write( "=-5&#8730;2/26+12&#8730;2/26=7&#8730;2/26<BR>\n" );
document.write( "cos(A-(pi/4))=7&#8730;2/26 </SPAN>\n" );
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