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Prove the following: 3sin-1x=sin-1(3x-4x3),x∈[-12,12] - Mathematics

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Question

Prove the following:

`3sin^(-1) x = sin^(-1)(3x - 4x^3), x in [-1/2, 1/2]`

Sum

Solution

To prove :  `3sin^(-1) x = sin^(-1)(3x - 4x^3), x in [-1/2, 1/2]`

Let x = sinθ. Then, `sin^(-1) x = 0`

We have

R.H.S = `sin^(-1) (3x - 4x^3) = sin^(-1) (3sin theta - 4 sin^3 theta)`

`= sin^(-1) (sin 3theta) =  sin^(-1) (3sin theta - 4 sin^3theta)`

= `3 theta = sin^(-1) (3sin theta - 4 sin^3theta)`

`= 3 sin^(-1) x = sin^(-1) (3sin theta - 4 sin^3theta)`

L.H.S

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Chapter 2: Inverse Trigonometric Functions - Exercise 2.2 [Page 47]

APPEARS IN

NCERT Mathematics [English] Class 12
Chapter 2 Inverse Trigonometric Functions
Exercise 2.2 | Q 1 | Page 47

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