Solve the trigonometric equation in the interval [0, 2π). give the exact value, if possible; otherwise, round your answer to two decimal places. (enter your answers as a comma-separated list.) for the following:
1.) 2 cos2(θ) + 19 cos(θ) + 9 = 0
2.) 7 cos(2θ) = 2
3. ) 9 sin(θ) − 4 = 0