Ex 2.1

Chapter 2 Class 12 Inverse Trigonometric Functions
Serial order wise

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### Transcript

Ex 2.1, 10 (Method 1) Find the principal value of cosec–1 (–√2) Let y = cosec–1 (– √2) y = −cosec–1 (√2) y = − 𝝅/𝟒 Since Range of cosec−1 is [−π/2,π/2] − {0} Hence, Principal Value is (−𝝅)/𝟒 We know that cosec−1 (−x) = − cosec −1 x Since cosec 𝜋/4 = √2 𝜋/4 = cosec−1 (√2) Ex 2.1, 10 (Method 2) Find the principal value of cosec–1 (–√2) Let y = cosec–1 (– √2) cosec y = – √2 cosec y = cosec ((−𝝅)/𝟒) Since Range of cosec−1 is [−π/2,π/2] − {0} Hence, Principal Value is (−𝝅)/𝟒 Rough We know that cosec 45° = √2 θ = 45° = 45 × 𝜋/180 = 𝜋/4 Since −√2 is negative Principal value is − θ i.e. (−𝜋)/4

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#### Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.