## lidya prove that cos4x - sin4x = cos2x 11 months ago 11 months ago

@lidya , hi :) $$\Huge \mathcal{\text{Welcome To OpenStudy}\ddot\smile}$$ The question you have asked belongs to maths section, http://openstudy.com/study#/groups/Mathematics This is feedback section used to give feedback and suggestions. Go to maths section and ask your question again, and please close this question here.