Q7
Vectors 3D & Lines
Line Through Intersection Parallel to Given Direction
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Let $\overrightarrow{\mathrm{a}} = \hat{i} + 2\hat{j} + \hat{k}$ and $\overrightarrow{\mathrm{b}} = 2\hat{i} + 7\hat{j} + 3\hat{k}$. Let $\mathrm{L}_1: \overrightarrow{\mathrm{r}} = (-\hat{i} + 2\hat{j} + \hat{k}) + \lambda\overrightarrow{\mathrm{a}},\ \lambda \in \mathbf{R}$ and $\mathrm{L}_2: \overrightarrow{\mathrm{r}} = (\hat{j} + \hat{k}) + \mu\overrightarrow{\mathrm{b}},\ \mu \in \mathbf{R}$ be two lines. If the line $\mathrm{L}_3$ passes through the point of intersection of $\mathrm{L}_1$ and $\mathrm{L}_2$, and is parallel to $\vec{a} + \vec{b}$, then $\mathrm{L}_3$ passes through the point:
(1) $(5, 17, 4)$
(2) $(2, 8, 5)$
(3) $(8, 26, 12)$
(4) $(-1, -1, 1)$