Q.

If the vertices of a parallelogram PQRS taken in order are P(3, 4), Q(-2, 3) and R(-3, -2), then the coordinates of its fourth vertex S are

1 (-2, -1)  
2 (-2, -3)  
3 (2, -1)  
4 (1, 2)  

Ans.

(3)

We know that the diagonals of a parallelogram bisect each other.

Therefore, midpoint of QS = midpoint of PR. Let the coordinate of S is (x, y)

(x-22,y+32)=(3-32,4-22)

x-22=3-32 and y+32=4-22

x-2=0  x=2

and y+3=2  y=-1

Hence, fourth vertex S are (2, -1).