calculate the slopes of the lines using the gradient formula
m = (y₂ - y₁ ) / (x₂ - x₁ )
(x₁, y₁ ) = A(- 4, - 1) and (x₂, y₂ ) = B(-1, 2 )
=
=
= 1
(x₁, y₁ ) = B(-1, 2) and (x₂, y₂ ) = (5, 1)
=
= -
(x₁, y₁) = C(5, 1 ) and (x₂, y₂ ) = D(1, - 3)
=
=
= 1
(x₁, y₁) = A(- 4, - 1) and (x₂, y₂) = D(1, - 3 )
=
= -
Quadrilateral ABCD is not a parallelogram since only one pair of opposite sides is parallel , that is AB and CD