document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=257796>Question 257796</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Find the area of the triangle ABC having vertices A(7,-4) B(3,1) C(-10,-8) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #189687 by </B><A HREF=/tutors/aboutme.mpl?userid=drk><B>drk(1908)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=drk><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=189687\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If you graph these out, you may notice that there are no right angles. This means we can use one of three formulas:<BR>\n" );
document.write( "(1) Hero's formula - approximate<BR>\n" );
document.write( "To use this we need the 3 distances. They are: sqrt(255), sqrt(61), sqrt(261)<BR>\n" );
document.write( "The semi perimeter, s, is about 12.79<BR>\n" );
document.write( "A = sqrt(s*(s-a)(s-b)(s-c))<BR>\n" );
document.write( "A = 50.5<BR>\n" );
document.write( "(2) matrices<BR>\n" );
document.write( "Lets use matricies. If we apply matrices, we get 50.5<BR>\n" );
document.write( "--<BR>\n" );
document.write( "(3) 1/2absinC<BR>\n" );
document.write( "This requires trig calculations, which I don't know you have seen.<BR>\n" );
document.write( "--<BR>\n" );
document.write( "So the area is 50.5. </SPAN>\n" );
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