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Mathematics · 2026 · 2 marks
Three Dimensional GeometryDirection Cosines and Direction Ratios of a Line2 marksApplyvery short answer
CBSE 2026 · Region 1 · Set 2 · Q21
A vector a of magnitude 14 has direction ratios <2,3,-6>. Find the projection of the vector a on i.
A vector $\displaystyle \vec{\mathrm{a}}$ of magnitude $\displaystyle 14$ has direction ratios $\displaystyle <2,3,-6>$. Find the projection of the vector $\displaystyle \overrightarrow{\mathrm{a}}$ on $\displaystyle \hat{\mathrm{i}}$.
Marking-scheme solution
Getting $\displaystyle \vec{\mathrm{a}} = 4\hat{\imath} + 6\hat{\jmath} - 12\hat{k}$
Projection of $\displaystyle \vec{\mathrm{a}}$ on $\displaystyle \hat{\imath} = \vec{\mathrm{a}} \cdot \hat{\imath} = 4$
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CBSE Class 12 Mathematics past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.