Find the period of the function y = 2cos(3x + π/4) - tan(2x), where x is measured in radians.
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Find the x-values between 0 and 2π (in radians) for which the cotangent function f(x) = cot x has the characteristics of oscillation, periodicity, and asymptotes.
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What is the standard deviation of the dataset {1, 4, 6, 8, 9}?