# The position vectors of the points A, B, C of a parallelogram ABCD are a, b, and c respectively. How do I express, in terms of a, b and, the position vector of D?

##### 1 Answer

Aug 5, 2018

#### Explanation:

Suppose that, the **position vector (pv)** of the point

We dnote this by

Now, we know from **Geometry** that, the **diagonals**

of a **parallelogram** **bisect** each other.

Therefore, the **mid-point** of the **diagonal** **same** as that of

the **diagonal**

But, the **pv.** of

Clearly,