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Show that the point $A(0,0)$, $B(2,5)$, $C(7,-3)$, $D(9,2)$ are vertices of the parallelogram and using determinants to find its area.

Ng Chung Tak
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Sneha Bhosale
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  • If you plot the points on a Cartesian plane and find the slope of the opposite sides to be equal, meaning that the lines are parallel, then you can prove it is a parallelogram. – Harnoor Lal Feb 08 '17 at 09:03
  • Then create a matrix whose columns are vectors representing the two non-parallel sides and compute its determinant. – SquirtleSquad Feb 08 '17 at 09:23

1 Answers1

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Note that $A$, $B$, $C$, $D$ are not in correct order.

Since $A+D=B+C=(9,2)$, $AD$ and $BC$ bisect each other.

Hence, $ABDC$ is a parallelogram.

$$\text{Area of }ABDC = \left| \vec{AB} \times \vec{AC} \right|$$

Ng Chung Tak
  • 18,990