If you plot the points you will find you have to use the distance formula. Pick out 2 pairs label them (x1,y1) (x2,y2) then plug it into the distance formula. The repeat for the other sides. So you should get (2,5) (4,3) plug into distance formula what is get it distance between those two points, then (4,3) (-2,-1) plug into distance formula to get an answer, lastly (-2,-1) (2,5) plug in. Now you have three answers add all together and here is your perimeter of a triangle.
