Which value must be added to the expression x2 + 12x to make it a perfect-square trinomial?

Determine whether the quadrilateral below is a parallelogram. justify/explain your answer (this means back it up! give specific information that supports your decision. writing just "yes" or "no" will result in no credit.)

Can someone tell me if this is perpendicular? !

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)