document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=756827>Question 756827</A>: <I><SPAN STYLE=\"word-break: break-all;\"> prove the following as an identity;\r<BR>\n" );
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document.write( "cos(a-b) - cos(a+b) = 2sin(a)sin(b) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #460518 by </B><A HREF=/tutors/aboutme.mpl?userid=Cromlix><B>Cromlix(4381)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Cromlix><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/cgi-bin/show-face.mpl?user=Cromlix><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=460518\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> cos(a - b) = cosacosb + sinasinb<BR>\n" );
document.write( "cos(a + b) = cosacosb - sinasinb<BR>\n" );
document.write( "= cosacosb + sinasinb -(cosacosb - sinasinb)<BR>\n" );
document.write( "= cosacosb + sinasinb - cosacosb + sinasinb)<BR>\n" );
document.write( "=        sinasinb + sinasinb<BR>\n" );
document.write( "=             2sinasinb Proved<BR>\n" );
document.write( "Hope this helps<BR>\n" );
document.write( ":-)<BR>\n" );
document.write( " </SPAN>\n" );
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