Уравния 4х-1=2(х+3) 5х+0.9=3(х-1.5) 4(3х-0.6)=-3(4х-0.8)

Question

Математика: Уравния 4х-1=2(х+3) 5х+0.9=3(х-1.5) 4(3х-0.6)=-3(4х-0.8)

dgony2003 · Accepted Answer

Во-первых, если cos x = 2√2/3, то cos^2 x = 8/9, sin^2 x = 1/9; sin x = 1/3. cos^2 (x-38) + cos^2 38 - 2cos(x-38)*cos x*cos 38 = = (cos x*cos 38+sin x*sin 38)*cos(x-38) + cos^2 38 - 2cos(x-38)*cos x*cos 38 = cos^2 38 + cos(x-38)*sin x*sin 38 + cos(x-38)*cos x*cos 38 - - 2cos(x-38)*cos x*cos 38 = = cos^2 38 + cos(x-38)*sin x*sin 38 - cos(x-38)*cos x*cos 38 = = cos^2 38 - cos(x-38)*(cos x*cos 38 - sin x*sin 38) = = cos^2 38 - cos(x-38)*cos(x+38) = = cos^2 38 - 1/2*(cos(x-38-x-38) + cos(x-38+x+38))...

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