English

∫1sinx-3cosxdx

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Question

`int 1/(sin x - sqrt3 cos x) dx`
Sum
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Solution

Given I = `int 1/(sin x - sqrt3 cos x) dx`

Let 1 = r cos θ and √3 = r sin θ

r = `sqrt(3 + 1) = 2`

And tan θ = √3 → θ = `pi/3`

=> `int 1/(sin x - sqrt3 cos x) dx = int 1/(rcos theta sin x - r sin theta cos x) dx`

= `1/r int 1/(sin (x - theta))dx`

= `1/r int cosec(x - theta)dx`

We know that `int cosec x  dx = log|tan (x/2 - pi/6)| + c`

`1/2 log |tan(x/2 - pi/6)| + c`

∴ I = `int 1/(sinx - sqrt3 cos x) dx`

`1/2 log |tan (x/2 - pi/6)| + c`

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Chapter 18: Indefinite Integrals - Exercise 19.23 [Page 117]

APPEARS IN

R.D. Sharma Mathematics Volume 1 and 2 [English] Class 12
Chapter 18 Indefinite Integrals
Exercise 19.23 | Q 14 | Page 117
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