Question

Sin^4x/4-cos^4x/4=1/2
Подробно

Answer 1

(sin²x/4-cos²x/4)(sin²x/4+cos²x/4)=1/2
-cosx/2*1=1/2
cosx/2=-1/2
x/2=+-2π/3+2πn
x=+-4π/3+4πn,n∈z
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cos²a-sin²a=cos2a
sin²a+cos²a=1