Q26 of 157 Page 737

If three consecutive vertices of a parallelogram ABCD are A(1, – 2), B(3, 6) and C(5, 10), find its fourth vertex D.


Coordinate of mid – point of AC = {(1 + 5)/2,(– 2 + 10)/2}


implies (3,4)


This is equal to the coordinates of mid – point of BD


3 = (3 + x)/2


6 = 3 + x


x = 3


4 = (6 + y)/2


8 = (6 + y)


y = 2


Hence, D(3, 2)


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