Sin^4x-cos^4y=sin^2x-cos^2x доказать тождество

Question

Sin^4x-cos^4y=sin^2x-cos^2x доказать тождество

Answer 1

Sin^4x-cos^4y=sin^2x-cos^2y
(sin^2x-cos^2y)(sin^2x+cos^2y)=sin^2x-cos^2y
sin^2x-cos^2y*1=sin^2x-cos^2y
sin^2x-cos^2y=sin^2x-cos^2y