CBSE 2023 · Region 2 · Set 1 · Q20 · 1 mark
Assertion (A) : If a line makes angles $\displaystyle \alpha, \beta, \gamma$ with positive direction of the coordinate axes, then $\displaystyle \sin ^{2} \alpha+\sin ^{2} \beta+\sin ^{2} \gamma=2$.
Reason (R): The sum of squares of the direction cosines of a line is $\displaystyle 1$ .
Official answer
From CBSE’s own marking scheme for this paper.
(A)
Both (A) and (R) are true and (R) is the correct explanation of (A).
Three Dimensional GeometryDirection Cosines and Direction Ratios of a LineAnalyseassertion_reasonmedium
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CBSE Class 12 Mathematics past-paper question from the 2023board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.