Solve the given equation. (Enter your answers as a comma-separated list. Let k be any integer. Round terms to three decimal places where appropriate. If there is no solution, enter NO SOLUTION.)
2 sin2(θ) + cos(θ) = 1
3 sin(2θ) − 5 sin(θ) = 0
4 sin(2θ) − 2 sin(θ) = 0
cos(2θ) = 5 sin(θ) − 2
PLEASE HELP ME WITH THESE FOUR! I HAVE BEEN STUCK ON THESE PROBLEMS FOREVER!