Prove that quadrilateral ABCD with the vertices A (2,1), B (1,3), C (-5,0) D (-4,-2) is a rectangle. Graph the rectangle and then use appropriate formulas to justify / prove your answer.

Answer:
Just find the distance of the vertices of the quadrilateral ( such as : AB, BC, CD DA )by using distance formula...
Then if opposite sides of quadrilateral is equal then it is rectangle .....
hope you understand...