document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=858028>Question 858028</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Express the sin (-140°) as a function of a positive acute angle\r<BR>\n" );
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document.write( "1) sin 40°<BR>\n" );
document.write( "2) tan 40°<BR>\n" );
document.write( "3) -sin 40°<BR>\n" );
document.write( "4) -tan 40° </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #516980 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=516980\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> -140 degrees is in the third quadrant.<BR>\n" );
document.write( "to turn that into a positive angle, add 360 to it to get:<BR>\n" );
document.write( "-140 degrees + 360 degrees is equal to 220 degrees.<BR>\n" );
document.write( "-140 degrees is equivalent to 220 degrees.<BR>\n" );
document.write( "to find the reference angle for 220 degrees, you would use the following formula:<BR>\n" );
document.write( "180 + x = 220<BR>\n" );
document.write( "solve for x to get:<BR>\n" );
document.write( "x = 220 - 180 which results in:<BR>\n" );
document.write( "x = 40 degrees.<BR>\n" );
document.write( "the sine is positive in the first quadrant but negative in the third quadrant.<BR>\n" );
document.write( "so the sin (-140) degrees is equal to the sin (220) degrees which is equal - the sine of (40) degrees. <BR>\n" );
document.write( "to confirm this is correct, use your calculator to find the sine of (220) degrees) and the sine of (-140) degrees and the sine of (40) degrees.<BR>\n" );
document.write( "you will find that the sin of (220) and (-140) degrees is the same and that both of them are equal to - sine of (40) degrees.<BR>\n" );
document.write( "the numbers from my calculator are:<BR>\n" );
document.write( "sin(220) = -.64278676097<BR>\n" );
document.write( "sin(-140) = -.6427876097<BR>\n" );
document.write( "sin(40) = .6427876097<BR>\n" );
document.write( "a picture of what the angle looks like is shown below:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" src = \"http://theo.x10hosting.com/2014/mar293.jpg\" alt=\"$$$\" </> </SPAN>\n" );
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