What is cot 2x cot 4x - cot 4x cot 6x - cot 6x cot 2x equal to

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Concept:

\(\rm cot (A + B) = \dfrac{cot A cot B - 1}{cot A + cot B}\)

Calculation:

Given,

(cot 2x ∙ cot 4x) - (cot 4x  cot 6x) - (cot 6x  cot 2x)

⇒ (cot 2x  cot 4x) - cot 6x [cot 4x + cot 2x]

(cot 2x  cot 4x) - cot (2x + 4x) [cot 4x + cot 2x]

(cot 2x  cot 4x) -  \((\rm \dfrac{cot 2x .cot 4x - 1}{cot 2x + cot 4x})\)× [cot 4x + cot 2x]

(cot 2x  cot 4x) - (cot 2x  cot 4 x - 1)

(cot 2x  cot 4x) - (cot 2x  cot 4x) + 1

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