Show that the line segments joining the mid-points of opposite sides of a quadrilateral bisects each other.

Explanation

Let `ABCD` is the given quadrilateral.

Please refer to video to see the diagram with their vector representation.

Let `O` is the origin and `E,F,G and H` are the mid points of sides of quadrilateral.

Then,

`vec(OE) = (veca+vecb)/2`

`vec(OF) = (vecb+vecc)/2`

`vec(OG) = (vecc+vecd)/2`

`vec(OH) = (veca+vecd)/2`

...