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Question： Solve [tan(2x) - tan(x)][cos(3x) + cos(x)] + 2cos(x) = 2, 0 ≤ x ≤ π Solution： [tan(2x) - tan(x)][cos(3x) + cos(x)] + 2cos(x) = 2, 0 ≤ x ≤ π  ... sin x + cos x = 1 (sin x + cos x)² = 1 ...... [ It also implies (sin x + cos x)² = (-1)² ] ... x = 0, π...