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By using the properties of the definite integral, evaluate the integral: ∫0π2sinx-cosx1+sinxcosxdx

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Question

By using the properties of the definite integral, evaluate the integral:

`int_0^(pi/2) (sin x - cos x)/(1+sinx cos x) dx`

Sum
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Solution

`I = int_0^(pi/2) (sin x - cosx)/(1+sinx cos x) dx`     ....(i)

`I = int_0^(pi/2) (sin (pi/2-x)-cos(pi/2-x))/(1 + sin(pi/2-x)cos(pi/2-x))dx`

`I = int_0^(pi/2) (cosx-sinx)/(1+cosxsinx)dx`    .....(ii)

Adding (i) and (ii), we get :

`2 I = int_0^(pi/2) ((sin x - cos x)/ (1 + sin x cos x) + (cos x - sin x)/ (1 + sin x cos x))  dx`

`2I = int_0^(pi/2)(sinx-cosx+ cosx - sinx)/(1 +sinxcosx)    dx`

`2I = 0 ⇒I=0`

`⇒ int_0^(pi/2) (sinx-cosx)/(1+sinxcosx)  dx=0`  

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Chapter 7: Integrals - Exercise 7.11 [Page 347]

APPEARS IN

NCERT Mathematics Part 1 and 2 [English] Class 12
Chapter 7 Integrals
Exercise 7.11 | Q 15 | Page 347

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