∫ 0 π / 2 l o g ⎝ ⎛ 4 + 3 c o s x 4 + 3 s i n x ⎠ ⎞ d x =
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Nice solution dude.
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thank you for the comment
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it is NCERT miscellaneous question ?? right !!
Consider the symmetry: The integrand may be written as I ( x ) = lo g ( 4 + 3 sin x ) − lo g ( 4 + 3 cos x ) . This function is symmetric under mirroring x ′ = π / 2 − x : I ( x ′ ) = I ( π / 2 − x ) = lo g ( 4 + 3 cos x ) − lo g ( 4 + 3 sin x ) = − I ( x ) . Thus we may split the integral as ∫ 0 π / 4 I ( x ) d x + ∫ π / 4 π / 2 I ( x ) d x = ∫ 0 π / 4 I ( x ) d x − ∫ 0 π / 4 I ( x ′ ) d x ′ = ∫ 0 π / 4 ( I ( x ) − I ( x ) ) d x = 0 .
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L e t I n = ∫ 0 π / 2 lo g 4 + 3 cos x 4 + 3 sin x d x t h e n b y ∫ b a f ( x ) d x = ∫ b a f ( a + b − x ) d x w e g e t I n = ∫ 0 π / 2 lo g 4 + 3 cos π / 2 − x 4 + 3 sin π / 2 − x d x a n d c a n b e w r i t t e n a s I n = ∫ 0 π / 2 lo g 4 + 3 sin x 4 + 3 cos x d x a n d 2 I n = I n + I n = ∫ 0 π / 2 lo g 4 + 3 sin x 4 + 3 cos x d x + ∫ 0 π / 2 lo g 4 + 3 cos x 4 + 3 sin x d x = ∫ 0 π / 2 ( lo g 4 + 3 sin x 4 + 3 cos x − lo g 4 + 3 sin x 4 + 3 cos x ) d x = ∫ 0 π / 2 0 d x = 0