InterviewSolution
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InterviewSolution
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A line makes an angel `theta`with each of thex-and z-axes. If the angel `beta,`which it makes with the y-axis, is such that`sin^2beta=3sin^2theta,t h e ncos^2theta`equalsa. `2/3`b. `1/5`c. `3/5`d. `2/5`A. `(2)/(3)`B. `(1)/(5)`C. `(3)/(5)`D. `(2)/(5)` |
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Answer» Correct Answer - c Here `sin^(2)beta=3sintheta" "(i)` By the question, `cos^(2)theta+cos^(2)theta+cos^(2)beta=1" "(ii)` `impliescos^(2)beta=1-2cos^(2)theta" "(iii)` Adding (i) and (iii), we get `1=1+3sin^(2)theta-2costheta` `=1+3(1-cos^(2)theta)-2cos^(2)theta` or `5cos^(2)theta=3` or `cos^(2)theta=(3)/(5)` |
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