document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1110589>Question 1110589</A>: <I><SPAN STYLE=\"word-break: break-all;\"> If sin(A)=-5/13. Find:\r<BR>\n" );
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document.write( "1. cos(2A)<BR>\n" );
document.write( "2. sin(2A)<BR>\n" );
document.write( "2. Cos(4A) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #725572 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=725572\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If sin(A)=-5/13. Find:\r<BR>\n" );
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document.write( "1. cos(2A)<BR>\n" );
document.write( "2. sin(2A)<BR>\n" );
document.write( "2. Cos(4A)<BR>\n" );
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document.write( "Step 1, find cos(A)<BR>\n" );
document.write( "cos(A) = sqrt(1 - sin^2) = 12/13 or -12/13<BR>\n" );
document.write( "The sine is negative in Q3 and Q4.  The cosine is negative in Q3 and + in Q4, so the sign and quadrant cannot be determined.<BR>\n" );
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document.write( "sin(2A) = 2sin(A)*cos(A)<BR>\n" );
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document.write( "cos(2A) = sqrt(1 - sin^2(2A))<BR>\n" );
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document.write( "cos(4A) = cos^2(2A) - sin^2(2A) </SPAN>\n" );
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