CosecA -2cot2AcosA=?

1 Answer
Jul 7, 2018

csc A - 2 cot 2A cos A = 2 sin AcscA2cot2AcosA=2sinA

Explanation:

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I'll assume that's cot 2Acot2A not cot^2 Acot2A

csc A - 2 cot 2A cos AcscA2cot2AcosA

= 1/sin A - {2 \cos 2A \cos A}/{sin 2A} =1sinA2cos2AcosAsin2A

= 1/sin A - {2 \cos 2A \cos A}/{2 sin A cos A}=1sinA2cos2AcosA2sinAcosA

= 1/{sin A} - { \cos 2A }/{2 sin A }=1sinAcos2A2sinA

= (1 - cos 2A)/{sin A} =1cos2AsinA

={ (sin ^2 A + cos ^2A) - (cos^2 A - sin ^2 A)}/{sin A} =(sin2A+cos2A)(cos2Asin2A)sinA

={ 2sin ^2 A }/{sin A} =2sin2AsinA

= 2sin A =2sinA