Find the principal values of the following questions:
cosce−1(−√2)
Let cosce−1(−√2)
We know that the range of principal value of cosec−1 θ is [−π2,π2]−{0},
∴ cosec θ=−√2=−cosecπ4=cosec(−π4) (∵ cosec(−θ)=−cosec θ)
⇒ θ=−π4, where θε[−π2,π2]−{0} ⇒ cosec−1(−√2)=−π4
Hence, the principal value of cosec−1(−√2) is−π4