Ответы и объяснения

2013-04-20T14:42:03+04:00

4-г

sin^4a-2sina^2cos^2a+cos^4a/(sina+cosa)^2=sin^2a-2sinacosa+cos^2a

sin^4a-2sin^2acos^2a+cos^4a/(sina+cosa)^2=(sina-cosa)^2

sin^4a-2sina^2cos^2a+cos^4a=(sina-cosa)^2*(sina+cosa)^2

(sin^2a-cos^2a)^2=(sin^2a-cos^2a)^2