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Last updated at Feb. 13, 2020 by Teachoo
Transcript
Ex 2.1, 7 Find the principal value of sec−1 (2/√3) Let y = sec−1 (2/√3) sec y = 2/√3 sec y = sec (π/6) Range of principal value of sec−1 is [0, π] – {𝜋/2} Hence, principal value of sec−1 (2/√3) is 𝝅/𝟔 Rough We know that cos 30° = √3/2 sec 30° = 2/√3 θ = 30° = 30 × 𝜋/180 = 𝜋/6 Since 2/√3 is positive Principal value is θ i.e. 𝜋/6
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