Find the perimeter of the rectangle ABC if point A (6; -8) B (13; -1) C (-2; 7).

We have the coordinates of three points:

A (6; -8), B (13; -1), C (-2; 7).

Let’s find the distances between the points, thereby determining the lengths of the sides of the triangle ABC:

| AB | = ((13 – 6) ^ 2 + (-1 + 8) ^ 2) ^ (1/2) = (49 + 49) ^ (1/2) = 98 ^ (1/2);

| AC | = ((-2 – 6) ^ 2 + (7 + 8) ^ 2) ^ (1/2) = (64 + 225) ^ (1/2) = 17;

| BC | = (-2 – 13) ^ 2 + (7 + 1) ^ 2) ^ (1/2) = (225 + 64) ^ (1/2) = 17;

Add the values:

P (ABC) = 98 ^ (1/2) + 17 + 17 = 34 + 7 * 2 ^ (1/2).