fe mas2ala mesh 3rfa a7elaha 5ales helppp!!

[alaa_92]

ana 3ndy mas2ala meganenany ba2alha 3 ayam bas besor3a 3lshan el emta7an bokra
prove that:
(cos(A+)^2+(cos(A+)^2=cos2Acos2B+1

[karim elmasry]

de eih el mas2ala de :S:S:S::S:S