Réponses

2013-10-16T20:53:11+02:00
Cos 2x+sin2x= 1
cos2x= 1-sin 2x
sin2x=1-cos2x
cos2x-sin2 x = 1-sin2x -sin2x = 1-2sin2x
cos2x-sin2x= cos2x-1+cos2x =2cos2x