Indefinite Integration 1 Question 11

12. The value of the integral 22sin2xxπ+12dx

(where, [x] denotes the greatest integer less than or equal to x ) is

(2019 Main, 11 Jan I)

(a) 4sin4

(b) 4

(c) sin4

(d) 0

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Solution:

  1. Let I=22sin2x12+xπdx

Also, let f(x)=sin2x12+xπ

Then, f(x)=sin2(x)12+xπ( replacing x by x)

=sin2x12+1xπ[x]=[x], if xI1[x], if xIf(x)=sin2x12+xπ=f(x)

i.e. f(x) is odd function

I=0aaf(x)dx=0, if f(x) is odd function 20af(x)dx, if f(x) is even function 



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