Complete the proof to show that ABCD is a parallelogram. On a coordinate plane, quadrilateral A B C D is shown. Point A is at (negative 2, negative 2), point B is at (negative 3, 4), point C is at (2, 2), and point D is at (3, negative 4). The slope of Line segment B C is StartFraction 4 minus 2 Over negative 3 minus 2 EndFraction = negative two-fifths The slope of Line segment A D is StartFraction negative 4 minus (negative 2) Over 3 minus (negative 2) EndFraction = StartFraction negative 4 + 2 Over 3 + 2 EndFraction = negative two-fifths The slope of Line segment C D is StartFraction 2 minus (negative 4) Over 2 minus 3 EndFraction = StartFraction 2 + 4 Over 2 minus 3 EndFraction = StartFraction 6 Over negative 1 EndFraction = negative 6 The slope of Line segment B A is StartFraction 4 minus (negative 2) Over negative 3 minus (negative 2) EndFraction = StartFraction 4 + 2 Over negative 3 + 2 EndFraction = StartFraction 6 Over negative 1 EndFraction = negative 6 and because the . Therefore, ABCD is a parallelogram because both pairs of opposite sides are parallel. lengths of consecutive sides are not equal slopes of opposite sides are equal lengths of opposite sides are equal slopes of consecutive sides are not equal