text: solve sin2x-2cosx=sinx -1? i don't even know where to start.  please help. sin2x - 2cosx = sinx - 1 2sinxcosx - 2cosx = sinx - 1 2cosx(sinx - 1) - (sinx - 1) = 0 (sinx - 1)(2cosx - 1) = 0 sinx = 1 or cosx = ½ so x = π/2, 3π/2 or x = π/3, 5π/3 (for 0 ≤ x ≤ 2π) ie x = π/3, π/2, 3π/2 , 5π/3 (for 0 ≤ x ≤ 2π)