Number four and explain how to find perimeter only using vertices

Perimeter= 34 units 

you could use a graphing calculator  (physical or online, i use desmos) or just graph it or use the distance formula between all the points (which would take a long time) and if you did decide to do that remember to use logic because finding the distance between the two opposite diagonal points is not part of the perimeter or finally you could count between the points, but like the distance formula only between the points that are going to be a part of the perimeter.