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