Question
cos−1x=tan−1√1−x2x, then:
Answer: Option C
:
C
Putting θ=cos−1x in R.H.S., we have
R.H.S =tan−1√1−x2x=tan−1√1−cos2θcosθ(0≤θ≤π)=tan−1sinθcosθ=tan−1tanθ=θ=cos−1x when −π2<θ<π2
i.e., when 0≤θ<π2
i.e., when 0<cosθ≤1 i.e., 0<x≤1.
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:
C
Putting θ=cos−1x in R.H.S., we have
R.H.S =tan−1√1−x2x=tan−1√1−cos2θcosθ(0≤θ≤π)=tan−1sinθcosθ=tan−1tanθ=θ=cos−1x when −π2<θ<π2
i.e., when 0≤θ<π2
i.e., when 0<cosθ≤1 i.e., 0<x≤1.
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