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I = ∫ 0 2 π 2 sin θ + cos θ + 2 7 sin θ − 4 cos θ + 3 d θ = ∫ 0 1 ( 2 ( 2 t ) + 1 − t 2 + 2 ( 1 + t 2 ) ) ( 1 + t 2 ) 2 ( 7 ( 2 t ) − 4 ( 1 − t 2 ) + 3 ( 1 + t 2 ) ) d t = ∫ 0 1 ( t 2 + 4 t + 3 ) ( t 2 + 1 ) 1 4 t 2 + 2 8 t − 2 d t = ∫ 0 1 ( t + 1 ) ( t + 3 ) ( t 2 + 1 ) 1 4 t 2 + 2 8 t − 2 d t = ∫ 0 1 ( t 2 + 1 6 t + 4 − t + 1 4 − t + 3 2 ) d t = 3 ln ( t 2 + 1 ) + 4 tan − 1 t − 4 ln ( t + 1 ) − 2 ln ( t + 3 ) ∣ ∣ ∣ ∣ 0 1 = 3 ln 2 + π − 4 ln 2 − 4 ln 2 − 3 ln 1 − 0 + 4 ln 1 + 2 ln 3 = π − 5 ln 2 + 2 ln 3 ≈ 1 . 8 7 Let t = tan 2 θ ⟹ d t = 2 sec 2 θ d θ ⟹ sin θ = 1 + t 2 2 t , cos θ = 1 + t 2 1 − t 2 By partial fraction decomposition