CBSE Class 12 Math 2012 Solved Paper

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Question : 7
Total: 29
Write the principal value of cos1(
1
2
)
- 2 sin1(
1
2
)

Solution:  
Principal value of cos1(
1
2
)
=
π
3

Principal value of sin1(
1
2
)
=
π
6

Hence principal value of cos1(
1
2
)
- 2 sin1(
1
2
)

=
π
3
2(
π
6
)

=
2π
3

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