A rectangle has all sides perpendicular to each other, so the product of slope of every adjacent line is equal to -1.

Given point in order are A(-4, -1), B(-2, -4), C(4, 0) and D(2, 3)

Slope of AB =

Slope of BC =

The slope of CD =

Slope of DA =

⇒slopeofAB × slopeofBC

Hence AB is perpendicular to BC

Slope of BC × slope of CD

Hence BC is perpendicular to CD

Slope of CD × slope of DA

Hence CD is perpendicular to DA

Slope of DA × slope of AB

Hence DA is perpendicular to AB.

All angles are 90°.

So this is a rectangle ABCD.