Sum of squares of direction cosines =1: cos290+cos260+cos2θ=1. So 0+41+cos2θ=1, giving cos2θ=43. Since θ is acute: cosθ=23, so θ=6π.
CUET UG 2023 — Mathematics Geometry
If a line makes angles 90 degree, 60 degree and θ with x,y and z axis respectively, where θ is acute, then value of θ is:
Held on 25 May 2023 · Verified 13 Jul 2026.
6π
4π
3π
2π
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Consider the line $\vec{r} = -2\hat{i} + 3\hat{j} + \hat{k} + \lambda(5\hat{i} - 3\hat{j} - \hat{k})$. Match List-I with List-II | List-I | List-II | |---|---| | (A) A point on the given line | (I) $\left(\frac{5}{\sqrt{35}}, \frac{-3}{\sqrt{35}}, \frac{-1}{\sqrt{35}}\right)$ | | (B) Direction ratios of the given line | (II) (2, 3, 1) | | (C) Direction cosines of the given line | (III) (5, -3, -1) | | (D) Direction ratios of a line perpendicular to given line | (IV) (-2, 3, 1) | Choose the correct answer from the options given below:
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