For this you're going to use distance formula
D= square root of (x2-x1)^2 + (y2-y1)^2
To prove this is a parallelogram ALL sides must equal the same or two sides + two sides must be the same.
Find the distance of JO, YS, JS, and OS. If you have too find the distance of JY and OY. Using the formula above. Hope this helps you. If you need further help I can assist you with a problem step by step
