Question
Find the vector equation of line passing through the point having position vector

$5 \hat{i}+4 \hat{j}+3 \hat{k}$ and having direction ratios $-3,4,2$.

Answer

Let $\mathrm{A}$ be the point whose position vector is $\bar{a}=5 \hat{i}+4 \hat{j}+3 \hat{k}$.

Let $\bar{b}$ be the vector parallel to the line having direction ratios $-3,4,2$

Then, $\bar{b}=-3 \hat{i}+4 \hat{j}+2 \hat{k}$

The vector equation of the line passing through $\mathrm{A}(\bar{a})$ and parallel to $\bar{b}$ is $\bar{r}=\bar{a}+\lambda \bar{b}$,

where λ is a scalar. ∴ the required vector equation of the line is

$\bar{r}=5 \hat{i}+4 \hat{j}+3 \hat{k}+\lambda(-3 \hat{i}+4 \hat{j}+2 \hat{k})$.

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