Answer/Step-by-step explanation:
Factor this. GCF=2
2(2cos2x+cos x-1)=0
2(2cos x -1)(cos x+1)=0 Set each factor equal to zero and solve
2cos x -1=0 Add 1 to both sides
2cos x =1 Divide by 2
cos x =1/2
x=π/3
x=5π/3
cos x+1=0 Subtract 1 from both sides
cos x=-1
x = π
