document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=890708>Question 890708</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 7pi/10 * cos 2pi/15 + sin 7pi/10 * sin 2pi/15= ???  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #539192 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=539192\">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 7pi/10 * cos 2pi/15 + sin 7pi/10 * sin 2pi/15= ???<BR>\n" );
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document.write( "Identity: cos(x-y)=cosxcosy+sinxsiny<BR>\n" );
document.write( "cos 7pi/10 * cos 2pi/15 + sin 7pi/10 * sin 2pi/15<BR>\n" );
document.write( "=cos(7&#960;/10-2&#960;/15)=cos(21&#960;/30-4&#960;/30)=cos(17&#960;/30) </SPAN>\n" );
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