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Венера Арзыкулова
СК
Сергей Кузин
[2cos^2(x)-1] - cos^2(x)=-1/4;
2cos^2(x)-cos^2(a)=-1/4+1; cos^2(x)=3/4; cosx=+-V3/2.
1) cos x =V3/2; x=+-pi/6+2pin, n---Z.
2) cos x=-V3/2; x=+-5pi/6+2pin, n---Z.
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[2cos^2(x)-1] - cos^2(x)=-1/4;
2cos^2(x)-cos^2(a)=-1/4+1; cos^2(x)=3/4; cosx=+-V3/2.
1) cos x =V3/2; x=+-pi/6+2pin, n---Z.
2) cos x=-V3/2; x=+-5pi/6+2pin, n---Z.