Хелп 2sin^2x-2cosx=5/2

sin^2(x) = 1-cos^2(x), 2*( 1-cos^2(x) ) - 2*cos(x) = 5/2, 4*( 1-cos^2(x) ) - 4*cos(x) = 5; 4 - 4*cos^2(x) - 4*cos(x) = 5; 4*cos^2(x) + 4*cos(x) + 1 = 0; (2*cos(x) + 1)^2 = 0; 2*cos(x) + 1 = 0; cos(x) = -1/2; x1 = arccos(-1/2) + 2*п*m, x2 = -arccos(-1/2) + 2*п*n, m,n целые. x1 = (п - (п/3)) + 2*п*m = (2п/3) + 2*п*m, x2 = (-2п/3) + 2*п*n.