Find the area of the triangle ABC having vertices A(7,-4) B(3,1) C(-10,-8)





The area of a triangle with vertices (a,b), (c,d), and (e,f) is





Do you know how to evaluate that determinant?  If not post again
asking how.



Note that if you take the vertices in counter-clockwise order around
the triangle, the absolute value bars are not necessary, because the
area will come out positive anyway and so sometimes the formula is 
given without the absolute value bars, and they tell you to always
take the vertices in counter-clockwise order; however if you include 
the absolute value bars, then it doesn't matter which order
you take the vertices.  Notice that I took them counter-clock-wise above,
and the absolute value bars were not really necessary.

Edwin