The coordinates of the vertices of parallelogram abcd are a(-3,2) , b (-2,-1) , c ( 4,1) and d ( 3,4). the slopes of which line segments could be calculated to show that abcd is a rectangle? 1) ab and dc 2) ab and bc 3) ad and bc 4) ac and bd when you say what answer you chose can you explain why that’s the answer in depth?

NOTE:
To show that a parallelogram is a rectangle, we need to show that ONE of the interior angles is a right angle.
Therefore we need to find the angle between two adjacent sides.

To find two adjacent sides in a parallelogram with vertices in counter-clockwise, we need two sides with a common vertex, for example, 
AB+BC, or BC+CD, or CD+DA, or DA+AB.

Any two sides without a common vertex are opposite sides.

20y5 times 2 is 1010 times -2 is -20, plus y