document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=921702>Question 921702</A>: <I><SPAN STYLE=\"word-break: break-all;\"> given sin alpha=-4/5, -pi/4 is less than alpha is less than 0; cos beta= -5/13, pi/2 is less than beta is less than pi, find sin (alpha - beta) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #559248 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=559248\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> given sin alpha=-4/5, -pi/4 is less than alpha is less than 0; cos beta= -5/13, pi/2 is less than beta is less than pi, find sin (alpha - beta)<BR>\n" );
document.write( "***<BR>\n" );
document.write( "sin a=-4/5 (-&#960;/4 < a < 0 )(Q4)<BR>\n" );
document.write( "cos a=3/5 (working with a (3-4-5) reference right triangle in quadrant IV)<BR>\n" );
document.write( "a&#8776;306.87&#730;<BR>\n" );
document.write( "..<BR>\n" );
document.write( "cos b=-5/13(&#960;/2 < b < &#960; )(Q2)<BR>\n" );
document.write( "sin b=12/13(working with a (5-12-13) reference right triangle in quadrant II)<BR>\n" );
document.write( "b&#8776;112.62&#730;<BR>\n" );
document.write( "..<BR>\n" );
document.write( "Identity: sin(a-b)=(sin a*cos b)-(cos a*sin b)=(-4/5*-5/13)-(3/5*12/13)=20/65-36/65=-16/65<BR>\n" );
document.write( "calculator check:<BR>\n" );
document.write( "a-b&#8776;306.87&#730;-112.62&#730;&#8776;194.25&#730;<BR>\n" );
document.write( "sin(a-b)&#8776;sin(194.25&#8776;-0.2462<BR>\n" );
document.write( "Exact value=-16/65&#8776;-0.2462 </SPAN>\n" );
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