document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=253351>Question 253351</A>: <I><SPAN STYLE=\"word-break: break-all;\"> please help me with this proof!!\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( "given-<BR>\n" );
document.write( "ab=3  bc= 2  ac=4\r<BR>\n" );
document.write( "\n" );
document.write( "prove angle 1 is acute </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #185639 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><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=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=185639\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> given-<BR>\n" );
document.write( "ab=3 bc= 2 ac=4 <BR>\n" );
document.write( "prove angle 1 is acute<BR>\n" );
document.write( "-----------------------<BR>\n" );
document.write( "There's no way to know which is angle 1, but the angle opposite the side=4 will be the largest.<BR>\n" );
document.write( "----------------<BR>\n" );
document.write( "Law of Cosines:<BR>\n" );
document.write( "ac^2 = ab^2 + bc^2 - 2*ab*bc*cos(angle)<BR>\n" );
document.write( "16 = 9 + 4 - 2*3*2*cos<BR>\n" );
document.write( "-12cos = 3<BR>\n" );
document.write( "cos = -1/4<BR>\n" );
document.write( "angle =~ 104.5º<BR>\n" );
document.write( "-------------<BR>\n" );
document.write( "That angle is not acute, the other 2 are. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );