The sides length of the square is 3 units, then the perimeter of the square is 12 units.
What is a square?
It is a polygon that has four sides. The sum of the internal angle is 360 degrees. In a square, opposite sides are parallel and all sides are equal and each angle is 90 degrees. And its diagonals are also equal and intersect at the mid-point.
If (-1, 2) and (2, -1) are two opposite vertices of a square, then the perimeter of the square will be
The other two vertices of the square will be
(-1, -1) and (2, 2)
Then the distance between the points (2, 2) and (2, -1) will be
[tex]\rm D = \sqrt{(2-2)^2+ (-1-2)^2}\\\\D = \sqrt{3^2}\\\\D = 3[/tex]
Then the perimeter of the square will be
Perimeter = 4 × 3
Perimeter = 12 units
More about the square link is given below.