Wie beweist man # cos ^ 4 (x) – sin ^ 4 (x) = cos (2x) #?
Wie beweist man # cos ^ 4 (x) – sin ^ 4 (x) = cos (2x) #? #LHS=cos^4x-sin^4x# #=(cos^2x+sin^2x)(cos^2x-sin^2x)# #=1*cos2x=cos2x=RHS#
Bette-Ann
Bette-Ann Wie beweist man # cos ^ 4 (x) – sin ^ 4 (x) = cos (2x) #? #LHS=cos^4x-sin^4x# #=(cos^2x+sin^2x)(cos^2x-sin^2x)# #=1*cos2x=cos2x=RHS#