Using the distance formula and thinking of each set of 2 points as 2 sides of a triangle joined by a right angle on a graph. To solve for the entire perimeter we have to find the distance between A and B, B and C, A and C then add them together.
The distance between A and B can be solved by seeing there is a difference of 2 between the Y coordinates and a difference of 11 between the X coordinates. Now we solve for the hypotenuse like a triangle. 2^2+11^2 is 125. Then take the sqrt of that 11.18≈11.2.
We do the same with B and C now. Y difference of 0 and x difference of 13 so sqrt of 13^2 is simply 13
Now a and c. Y difference of 2 and x difference of 2. 2^2 +2^2 is 8 so sqrt 8 is 2.8
We add those all together which is a total permiter of 27
