First, we calculate the lengths of each line using the distance formula.
AB = (3 - -5) = 8
CA = (1 - -5) = 6
CB can be calculated using the hypotenuse equation:
CB = sqrt (AB^2 + CA^2)
CB = sqrt (8^2 + 6^2)
CB = 10
The perimeter is therefore:
perimeter = AB + CA + CB = 8 + 6 + 10
perimeter = 24 units
C. 24 units
so notice, the sides AB and AC you can pretty much count them off the grid.
now, to get the CB side.
sum all three sides up, and that's the perimeter of the triangle.