document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=888776>Question 888776</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Use a sum or difference formula to find the exact value of the following.\r<BR>\n" );
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document.write( "cos(5pi/7)cos(13pi/28) + sin(5pi/7)sin(13pi/28) = </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #537675 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=537675\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Use a sum or difference formula to find the exact value of the following. <BR>\n" );
document.write( "cos(5pi/7)cos(13pi/28) + sin(5pi/7)sin(13pi/28)<BR>\n" );
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document.write( "Identity: cos(x-y)=cosx*cosy+sinx*siny<BR>\n" );
document.write( "cos(5pi/7)cos(13pi/28) + sin(5pi/7)sin(13pi/28)=cos(5&#960;/7-13&#960;/8)=cos(40&#960;/56-91&#960;/56)=cos(-51&#960;/56) </SPAN>\n" );
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