Fig. 7.32.
Co-ordinates of the mid-point of AC are :
Co-ordinates of the mid-point of BD are
We know that the diagonals of rhombus bisect each other.
Therefore, co-ordinates of mid-point of AC = co-ordinates of mid-point of BD
Hence, the co-ordinates of the fourth vertex is (-3, -2).
Case II. Test for square :
Clearly, AC ≠ BD.
So, ABCD is not a square.