11. Find the side and diagonals of the square

The points \(A(9, 8)\), \(B(12, 8)\), \(C(12,11)\) and \(D(9,11)\) in order are the vertices of a square. Find the value of distance and diagonals of the square.

 

The distance between the points is  and the diagonal is √18√16√17√21 this is equal to all the points which make the square shape.