6cos^2(x) - 2sin^2(x) = 6cos^2(x) - 1 + 1 - 2sin^2(x) 1 - 2sin^2(x) = 1 - sin^2(x) - sin^2(x) = 2cos^2(x) - 1 6cos^2(x) - 1 + 2cos^2(x) - 1 = 8cos^2(x) - 2
