The points (8, 4), (5, 7), (−1, 1), (2, −2) form
a parallelogram
a rectangle
a rhombus
a square
A(8,4),B(5,7),C(−1,1),D(2,−2)
A+C=B+D
AB↔ slope =3−3=−1 BC↔ =−6−6=1 AB↔⊥BC↔
AB=9+9=18
BC=36+36=72
AB≠BC
∴ A,B,C,D form a rectangle