Comment démontrer les identités de cos a (tan a -1)= sin a (1- cotg a)

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Grade: Education Subject: mathematiques

Comment démontrer les identités de cos a (tan a -1)= sin a (1- cotg a)

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cos a (tan a -1)=cosa[(sina/cosa)-1]=cosa[(sina-cosa)/cosa)]=sina - cosa

 

 sin a (1- cotg a)=sina[1-(cosa/sina)]=sina[(sina-cosa)/sina]=sina-cosa

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cos a (tan a -1)= sin a (1- cotg a)