Since there are three points, the figure is a triangle. The perimeter is the total distance around the triangle. Imagine yourself walking from point x to point y to point z then back to point x. The perimeter is the distance you would walk. The formula for the distance between two points (x1,y1) and (x2,y2) is:
distance = √[ (x2-x1)2+(y2-y1)2 ]
Use the formula to compute the distance between points x and y, y and z, and z and x then add them together to get the perimeter.
