मराठी

Evaluate the definite integral: ∫π6π3 sinx+cosxsin2xdx - Mathematics

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प्रश्न

Evaluate the definite integral:

`int_(pi/6)^(pi/3)  (sin x + cosx)/sqrt(sin 2x) dx`

बेरीज
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उत्तर

Let `I = int_(pi/6)^(pi/3) (sin x + cos x)/sqrt(sin 2x)`dx

`= int_(pi/6)^(pi/3) (sin x + cos x)/sqrt(1 - (1 - sin 2x))`dx

`= int_(pi/6)^(pi/3) (sin x + cos x)/sqrt(1 - (sin x - cos x)^2)`dx

Put sin x - cos x = t

(cos x + sin x) dx = dt

When `x = pi/6, t = sin  pi/6 - cos  pi/6`

`= 1/2 - sqrt3/2`

`= (sqrt3 - 1)/2`

When x = `pi/3, t = sin = pi/3 - cos  pi/3`

`= sqrt3/2 - 1/2`

`(sqrt3 - 1)/2`

∴ `I = int_(1/2 - sqrt3/2)^(sqrt3/2-1/2) dt/sqrt(1-t^2) = [sin^-1 t]_(1/2-sqrt3/2)^(sqrt3/2-1/2)`

`= sin^-1(sqrt3/2 - 1/2) - sin^-1 (1/2 - sqrt3/2)`

`= sin^-1 (sqrt3/2 - 1/2) + sin^-1 (sqrt3/2 - 1/2)`

`= 2 sin^-1  1/2 (sqrt3 - 1)`

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पाठ 7: Integrals - Exercise 7.12 [पृष्ठ ३५३]

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एनसीईआरटी Mathematics Part 1 and 2 [English] Class 12
पाठ 7 Integrals
Exercise 7.12 | Q 28 | पृष्ठ ३५३

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