document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=368413>Question 368413</A>: <I><SPAN STYLE=\"word-break: break-all;\"> What is the solution for the exact value of cos195 degrees? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #262547 by </B><A HREF=/tutors/aboutme.mpl?userid=nyc_function><B>nyc_function(2741)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=nyc_function><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=nyc_function><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=262547\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Find the exact value of cos195 degrees.\r<BR>\n" );
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document.write( "The key is to write 195 degrees as the sum or difference of two numbers whose sine and cosine are known.\r<BR>\n" );
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document.write( "cos195 = cos(45 + 150).\r<BR>\n" );
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document.write( "NOTE: 45 + 150 = 195.\r<BR>\n" );
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document.write( "We need to use the sum formula for cosine.\r<BR>\n" );
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document.write( "We use this: cos(A + B) = cosAcosB - sinAsinB\r<BR>\n" );
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document.write( "Let A = 45 and B = 150\r<BR>\n" );
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document.write( "cos(45 + 150) = cos45cos150 - sin45sin150\r<BR>\n" );
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document.write( "If you memorized the unit circle (as you should to make your trig life easier), you will know the following:\r<BR>\n" );
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document.write( "cos45 = sqrt[2]/2\r<BR>\n" );
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document.write( "cos150 = -sqrt[3]/2\r<BR>\n" );
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document.write( "sin45 = sqrt[2]\r<BR>\n" );
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document.write( "sin150 = 1/2\r<BR>\n" );
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document.write( "cos(45 + 150) = sqrt[2]/2 * -sqrt[3]/2 - sqrt[2]/2 * 1/2\r<BR>\n" );
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document.write( "cos(45 + 150) = (-sqrt[6] - sqrt[2])/4\r<BR>\n" );
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document.write( "So, the exact value of cos195 degrees is (-sqrt[6] - sqrt[2])/4\r<BR>\n" );
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document.write( "mrfeliz.webs.com\r<BR>\n" );
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document.write( " </SPAN>\n" );
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