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For a line with vector equation $\bar r=\bar a+\lambda\bar b$, which statement is correct?
A$\bar a$ is a direction vector and $\bar b$ is the position vector of a fixed point
BBoth $\bar a$ and $\bar b$ are position vectors of fixed points on the line
C$\bar a$ is the position vector of a fixed point on the line and $\bar b$ is a direction vector parallel to the line
D$\lambda$ must be a vector
Answer & Solution
Correct answer: C. $\bar a$ is the position vector of a fixed point on the line and $\bar b$ is a direction vector parallel to the line
In $\bar r=\bar a+\lambda\bar b$, the vector $\bar a$ locates a fixed point on the line and $\bar b$ gives its direction. The parameter $\lambda$ is a scalar, not a vector.
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