Приведите к виду произведения cos2x-cos4x-cos8x​

cos2x(1-2cos6x)

Объяснение:

cos4x=cos(6x-2x)=cos6xcos2x+sin6xsin2x

cos8x=cos(6x+2x)=cos6xcos2x-sin6xsin2x

cos2x-cos6xcos2x-sin6xsin2x-cos6ccos2x+sin6xsin2x=cos2x-2cos6xcos2x=

cos2x(1-2cos6x)