document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=923528>Question 923528</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find the exact value, given that sin A= -4/5, with A in quadrant IV, tan B= 7/24 with B in quadrant III, and cos C= -5/13 with C in quadrant II. <BR>\n" );
document.write( "cos2A\r<BR>\n" );
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document.write( "I have tried doing it but i end up with cos25/169-sin16/25. I'm not sure that it is correct. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #560156 by </B><A HREF=/tutors/aboutme.mpl?userid=ewatrrr><B>ewatrrr(24785)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ewatrrr><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=ewatrrr><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=560156\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> sin A= -4/5 (quadrant IV)  cos A = 3/5 <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%285%5E2+-+4%5E2%29+=+3 ALIGN=MIDDLE  ALT=\"sqrt%285%5E2+-+4%5E2%29+=+3\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "cos2A  = cos^2A - sin^2 A = (3/5)^2 - (-4/5)^2<BR>\n" );
document.write( "........<BR>\n" );
document.write( "tan B= 7/24 with B in quadrant III, <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%287%5E2+%2B+24%5E2%29+=+25 ALIGN=MIDDLE  ALT=\"sqrt%287%5E2+%2B+24%5E2%29+=+25\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "sin B = -7/25, cos B = -24/25<BR>\n" );
document.write( ".......<BR>\n" );
document.write( "cos C= -5/13 with C in quadrant II. , sin C = 12/13  <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=sqrt%2813%5E2+-+5%5E2%29+=+12 ALIGN=MIDDLE  ALT=\"sqrt%2813%5E2+-+5%5E2%29+=+12\"   DISABLED_style= \"max-width:90%; height:auto;\" > </SPAN>\n" );
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