Задача 14267 cos4x-sin4x=1...

u514123215

11.03.2017

cos4x-sin4x=1

u802345134

11.03.2017

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cos^4x-sin^4x=1/2
(cos^2x+sin^2x)*(cos^2x-sin^2x)=1/2
(cos^2x+sin^2x) = 1 = >
1*(cos^2x-sin^2x) = 1/2
(cos^2x-sin^2x)=1/2
cos^2x=1-sin^2x = >
1-sin^2x-sin^2x=1/2
2*sin^2x=1/2
sin^2x=1/4
sinx=1/2
sinx= -1/2