document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=863196>Question 863196</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Use a sum or difference formula to determine the value of the trigonomic function\r<BR>\n" );
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document.write( "cot(-7&#960;/12) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #520266 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=520266\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Use a sum or difference formula to determine the value of the trigonomic function <BR>\n" );
document.write( "cot(-7&#960;/12) <BR>\n" );
document.write( "*** <BR>\n" );
document.write( "cos(-7&#960;/12)=cos(7&#960;/12)=cos(3&#960;/12+4&#960;/12)=cos(&#960;/4+&#960;/3)<BR>\n" );
document.write( "Identity: cos(x+y)=cosxcosy-sinxsiny)<BR>\n" );
document.write( "cosx=cos(&#960;/4)=&#8730;2/2<BR>\n" );
document.write( "cosy=cos(&#960;/3)=1/2<BR>\n" );
document.write( "sinx=sin(&#960;/4)=&#8730;2/2<BR>\n" );
document.write( "siny=sin(&#960;/3)=&#8730;3/2<BR>\n" );
document.write( "cos(x+y)=&#8730;2/2*1/2-&#8730;2/2*&#8730;3/2=&#8730;2/4-&#8730;6/4=(&#8730;2-&#8730;6)/4<BR>\n" );
document.write( "...<BR>\n" );
document.write( "calculator check:<BR>\n" );
document.write( "cos(-7&#960;/12)&#8776;-0.2588…<BR>\n" );
document.write( "exact value=(&#8730;2-&#8730;6)/4&#8776;-0.2588…<BR>\n" );
document.write( " </SPAN>\n" );
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