Question 1207839
<pre>
It's always a good idea to draw a graph if the question is about points 
and lines.  The red line is AB, the green line is BC, The black line is
AC. I drew a little off from the others, but it's really the sum of the
other two lines. The other tutor has told you enough about how you are 
to prove what you want with the distance formula.
{{{drawing(400,500,-5,3,-3,7, grid(1),

circle(-4,6,.1), circle(-1,2,.1), circle(2,-2,.1) ,
circle(-4,6,.075), circle(-1,2,.075), circle(2,-2,.075) ,
circle(-4,6,.05), circle(-1,2,.05), circle(2,-2,.05),

locate(-4.2,5.9,A), locate(-1.2,1.9,B), locate(1.9,-2.1,C) ,
line(-4,6+.08,2,-2+.08),

red(line(-4,6-.06,-1,2-.06)),green(line(-1,2-.06,2,-2-.06)))

}}} 

Edwin</pre>