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Example 3 - Chapter 2 Class 12 Inverse Trigonometric Functions - Part 3

Example 3 - Chapter 2 Class 12 Inverse Trigonometric Functions - Part 4

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Example 3 Show that (ii) sin−1 (2x√(1−𝑥2)) = 2 cos−1x Solving L.H.S. sin−1 ( 2x √(1−𝑥2) ) Putting x = cos θ = sin−1 ("2 cos θ " √(𝟏−𝒄𝒐𝒔𝟐" θ" )) = sin−1 ("2 cos θ " √(𝒔𝒊𝒏𝟐" θ" )) = sin−1 (2 cos θ sin θ) = sin−1 (sin 2θ) We need to make 2x √(𝟏−𝒙𝟐) in terms of sin When we get √(1−𝑥2) , we put x = cos θ or sin θ = 2θ = 2 × cos−1 x = 2 cos−1 x = R.H.S. Since L.H.S. = R. H. S. Hence proved As x = cos θ cos−1 x = θ

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.