The position vector of the **centroid** of triangle with vertices $A(\vec a),\ B(\vec b),\ C(\vec c)$ is:
- $(\vec a + \vec b + \vec c)/3$
- $(\vec a + \vec b + \vec c)/2$
- $\vec a + \vec b + \vec c$
- $(\vec a \cdot \vec b \cdot \vec c)/3$
Show answer and solution
Correct answer: A. $(\vec a + \vec b + \vec c)/3$
Centroid $G$ divides each median internally in ratio 2:1, giving $\vec g = (\vec a + \vec b + \vec c)/3$.