SubArea: Trigonometric equations and inequalitiesLevel: CProject ID: 1003086105Accepted: 1Clonable: 0Easy: 0How many solutions does the equation \( 2\cos^2 x - \cos x - 1 = 0 \) have in the interval \( [-\pi;3\pi] \)?\( 6 \)\( 4 \)\( 2 \)\( 3 \)
