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

Explanation

To show that the line segments joining the midpoints of opposite sides of a quadrilateral bisect each other, we can follow these steps:

### Step 1: Define the Quadrilateral
Let the vertices of the quadrilateral be represented by position vectors:
- Vertex A: \(\vec{A}\)
- Vertex B: \(\vec{B}\)
- Vertex C: \(\vec{C}\)
- Vertex D: \(\vec{D}\)
...