document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1074123>Question 1074123</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Prove that <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28sin%28a%2Bb%29%29%2F%28tana%2Btanb%29=cosacosb+ ALIGN=MIDDLE  ALT=\"%28sin%28a%2Bb%29%29%2F%28tana%2Btanb%29=cosacosb+\"   DISABLED_style= \"max-width:90%; height:auto;\" > using only the left side. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #688848 by </B><A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><B>josgarithmetic(39625)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josgarithmetic><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=688848\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28sin%28a%29cos%28b%29%2Bcos%28a%29sin%28b%29%29%2F%28sin%28a%29%2Fcos%28a%29%2Bsin%28b%29%2Fcos%28b%29%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=%28%28sin%28a%29cos%28b%29%2Bcos%28a%29sin%28b%29%29%2F%28cos%28b%29sin%28a%29%2Bcos%28a%29sin%28b%29%29%29%28cos%28a%29cos%28b%29%29 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "If you look at the fraction on the left carefully, you will easily make the steps to show that it is equal to 1.<BR>\n" );
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document.write( "Used angle sum identity  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sin%28a%2Bb%29=sin%28a%29cos%28b%29%2Bcos%28a%29sin%28b%29 ALIGN=MIDDLE  ALT=\"sin%28a%2Bb%29=sin%28a%29cos%28b%29%2Bcos%28a%29sin%28b%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
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