parallelogram vector C4

Hello, I was stuck on this question. I didnt get how you know which point is where and also how the sides relate to each other? do opposite sides have same direction vector and same magnitude?
Thanks

Yes. Within a parallelogram the opposite sides have the same magnitude, however their direction vectors should be a multiple of $\pm 1$ from each other (in order to keep the magnitudes equal), it just depends how you look at it. Furthermore, the opposing angles are the same if as well wish you wish to that the angle approach. ABCD just means you have a point A which goes to B, then B to C, then C to D and from D back to A, and this configuration should form a parallelogram.

Also remember that if you're working with angles, your direction vectors should ways go head-to-head or tail-to-tail.

Thanks. What would be your working for this? if you have time please