math
posted by alex .
show that the triangle with verticies A(8,5) B(1,2) C(3,2) is a right triangle, and find its area.
the answer to the area is : 28.
please show me how to show its a right triangle, thanks!

compute the side lengths.
You know that if the sides obey a^2 + b^2 = c^2, it is a right triangle!