document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=211795>Question 211795</A>: <I><SPAN STYLE=\"word-break: break-all;\"> in triangle ABC,a=7.8, b=4.2, c=3.9. find B to the nearest tenth.\r<BR>\n" );
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document.write( "a)15.1 degrees\r<BR>\n" );
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document.write( "b)148.7 degrees\r<BR>\n" );
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document.write( "c)78.9 degrees\r<BR>\n" );
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document.write( "d)16.2 degrees </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #160178 by </B><A HREF=/tutors/aboutme.mpl?userid=HyperBrain><B>HyperBrain(694)</B></A><img src=\"/images/stars/stars-11.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=HyperBrain><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=160178\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> We use cosine law to solve this problem:<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=b%5E2=a%5E2+%2B+c%5E2+-2ac%2Acos+B ALIGN=MIDDLE  ALT=\"b%5E2=a%5E2+%2B+c%5E2+-2ac%2Acos+B\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "---<BR>\n" );
document.write( "Solving for cos B,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=cos+B=%28a%5E2+%2B+c%5E2+-+b%5E2%29%2F%282ac%29%0D%0A++++++++=%287.8%5E2+%2B+3.9%5E2+-+4.2%5E2%29%2F%282%2A7.8%2A3.9%29=0.9601 ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "B=arc cos 0.9601=<u>16.2 degrees</u> </SPAN>\n" );
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