alleryThe position vector of the **midpoint** of the segment joining points with position vectors $\vec a$ and $\vec b$ is:
A$(\vec a + \vec b)/2$
B$(\vec a - \vec b)/2$
C$\vec a \cdot \vec b$
D$|\vec a| + |\vec b|$
Answer & Solution
Correct answer: A. $(\vec a + \vec b)/2$
Midpoint formula: set m = n = 1 in the section formula to get $\vec r = (\vec a + \vec b)/2$.
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