document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=388642>Question 388642</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Please help!\r<BR>\n" );
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document.write( "If cos x = 0.8, what is a value of tan 1/2x?<BR>\n" );
document.write( "Thanks </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #274996 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=274996\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If cos x = 0.8, what is a value of tan 1/2x?<BR>\n" );
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document.write( "tan(x/2) = sin(x)/(1+cos(x))<BR>\n" );
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document.write( "If cos(x) = 4/5, x = 4 and r = 5<BR>\n" );
document.write( "Then y = sqrt[5^2-4^2] = 3<BR>\n" );
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document.write( "So, sin(x) = 3/5<BR>\n" );
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document.write( "tan(x/2) = (3/5)/(1+(4/5)) = (3/5)/(9/5) = 1/3<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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