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CBSE Class 12 Math 2020 Outside Delhi Set 3 Solved Paper

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Note : Except for the following questions, all the remaining questions have been asked in the previous sets.
SECTION - A
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Question : 1
Total: 11
The value of tan−1[‌
1
2
cos−1(‌
√5
3
)] is
Solution:     👈: Video Solution
y=tan[‌
1
2
cos−1(‌
√5
3
)]
Let, x=cos−1(‌
√5
3
)
⇒cos‌x=‌
√5
3

∴y=tan‌
1
2
x
y=tan‌
x
2

y=√‌
1−cos‌x
1+cos‌x
=√‌
1−
√5
3
1+‌
√5
3

=√‌
3−√5
3+√5

rationalizing the factor, we get,
y=‌
3−√5
2
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