In here, we will use the slope formula
in order to prove that ABCD is a parallelogram. The slope of AB must be equal
to CD and the slope of BC must be equal to DA. Using the formula m = (y1-y2) /
(x1-x2), we obtain the slope for AB = 0/4, BC = 1, CD = 0/4, DA = 1. We can say that ABCD is a parallelogram as it satisfies AB = CD, and BC = DA
