Q57 / 150 · MHT CET 2009 · Mathematics

If the line $\overrightarrow{\mathrm{OR}}$ makes angles $\theta_{1}, \theta_{2}, \theta_{3}$ with the planes XOY, YOZ, ZOX respectively, then $\cos ^{2} \theta_{1}+\cos ^{2} \theta_{2}+\cos ^{2} \theta_{3}$ is equal to

  • Correct answer
    A
    1
  • B
    2
  • C
    3
  • D
    4

Solution

If line $\overrightarrow{\text { OR }}$ makes angles $\theta_{1}, \theta_{2}, \theta_{3}$ with the planes XOY, YOZ, ZOX respectively, then $\cos ^{2} \theta_{1}+\cos ^{2} \theta_{2}+\cos ^{2} \theta_{3}=1$

Hence, the correct answer is option: 'A'.

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