Q24 of 184 Page 10

The area of a parallelogram is 12 square units. Two of its vertices are the points A(-1, 3) and B (-2, 4). Find the other two vertices of the parallelogram, if the point of intersection of diagonals lies on x-axis on its positive side.

Given: The area of a parallelogram is 12. A(-1, 3) and B(-2, 4)


To find: Find the other two vertices of the parallelogram.


Let C is (x, y) and A(-1, 3)


Since, AC is bisected at P, y coordinate ( when p = 0)


Then,


y = -3


So, Coordinate of C is (x, -3)


Now, Area of parallelogram ABCD = area of triangle ABC + Area of triangle BAD


Since, 2(Area of triangles) = area of parallelogram


We have, A(-1, 3) B(-2, 4) and C(x, -3)


Now, Area of triangle


Then,


Area of triangle ABC


6


6


12 = 5 - x


So, x = -7


Hence, Coordinate of C is (-7, -3)


In the same we will calculate for D


Let D is (x, y) and A(-2, 4)


Since, BD is bisected at Q, y coordinate ( when Q = 0)


Then,


y = -4


So, Coordinate of C is (x, -4)


We have, A(-1, 3) B(-2, 4) and C(x, -4)


Now, Area of triangle


Then,


Area of triangle ABC


6


6


12 = 6 - x


So, x = -6


Hence, Coordinate of D is (-6, -4)


Hence, C (-7, -3) and D(-6, -4)


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