Find all solutions of the equation in the interval 0 2pi Ent

Find all solutions of the equation in the interval [0, 2pi). (Enter your answers as a comma-separated list. If there is no solution, enter NO SOLUTION.) 9 cos^3 x = 9 cos x

Solution

9cos³x =9cosx

9cos³x - 9cosx=0

9cosx(cos²x -1)=0

9cosx(-sin²x)=0

cosx =0, sin²x =0

x =/2 ,3/2 , x=0,

=> x =0 ,/2 ,,3/2