document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1019407>Question 1019407</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Proof the identity\r<BR>\n" );
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document.write( "What happens if you get Cos (A-360).  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #635337 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=635337\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> cosine (a - 360) should be equal to cosine (a).\r<BR>\n" );
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document.write( "this is because the graph of cosine (a) will repeat every 360 degrees.\r<BR>\n" );
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document.write( "here's what the graph looks like.\r<BR>\n" );
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document.write( "<IMG STYLE=\"max-width:80%;\" src = \"http://theo.x10hosting.com/2016/021202.jpg\" alt=\"$$$\" </>\r<BR>\n" );
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document.write( "the graph is of the equation y = cos(x).\r<BR>\n" );
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document.write( "there are 2 vertical lines.\r<BR>\n" );
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document.write( "one is at x = 30 and one is at x = 30 - 360.\r<BR>\n" );
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document.write( "30 - 360 is equal to - 330 as sh own on the graph.\r<BR>\n" );
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document.write( "you can see that the cosine function is the same for both angles.\r<BR>\n" );
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document.write( "using the trigonometric identity function of cos(a-b) should get you the same result when you assume that b is equal to 360 degrees.\r<BR>\n" );
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document.write( "the identity function is:\r<BR>\n" );
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document.write( "sin(a - b) = sin(a)cos(b) – cos(a)sin(b)\r<BR>\n" );
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document.write( "when b = 360 degrees, then\r<BR>\n" );
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document.write( "sin(360) = 0<BR>\n" );
document.write( "cos(360) = 1\r<BR>\n" );
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document.write( "the formula of sin(a - b) = sin(a)cos(b) – cos(a)sin(b) becomes:\r<BR>\n" );
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document.write( "sin(a - 360) = sin(a)cos(360) - cos(a)sin(360) which becomes:\r<BR>\n" );
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document.write( "sin(a - 360) = sin(a)*1 - cos(a)*0 which becomes:\r<BR>\n" );
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document.write( "sin(a - 360) = sin(a)\r<BR>\n" );
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document.write( " </SPAN>\n" );
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