is triangle DEF with verticies D(-3,-4), E(2.-5), F(0,1) a right triangle?
Ah, a slightly different twist :)
For the third time, find the squares of the lengths of the three sides.
If the sum of the squares of the two smaller sides = the square of the third side, it is.
like if
c^2 = a^2 + b^2 it is right