#### Triple angle identity for cotangent

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Triple angle identity for cotangent function is used to represent cotangent of a triple angle in terms of cotangent of one-third of the triple angle. More specifically, cotangent of a triple angle equals to the difference between three cotangent of one-third of the triple angle and cotangent of one-third of the triple angle to power three divided by 1 minus three cotangent of one-third of the triple angle to power two.

\cot 3\alpha =\dfrac{3\cot \alpha -\cot^3\alpha }{1-3\cot^2\alpha }

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