Geometry
posted by EKH on .
quadrilateral A B C D on a graph. Point A is at ( 5, 1), Point B is at ( 6, 1), Point C is at (4, 3), Point D is at (7, 5).
Prove the quadrilateral is a parallelogram by using Theorem 58; if one pair of opposite sides of a quadrilateral is both congruent and parallel, then it is a parallelogram.

figure the length and slope of AB and CD. If they match, it's a ogram.