SOLUTION: trigonometry equations cos^3x=cosx i dont know what to do please help me.

Question 606190: trigonometry equations
cos^3x=cosx
i dont know what to do please help me.

Answer by htmentor(1343) (Show Source): You can put this solution on YOUR website!
cos^3x=cosx
This equation can be factored as cos(x)(cos^2(x) - 1) = 0
The RHS will be equal to 0 if either of the two factors is equal to 0.
So we have cos(x) = 0 and cos^2(x) - 1 = 0
cos(x) = 0 -> x = multiples of
cos^2(x) - 1 = 0 can be factored as (cos(x)+1)(cos(x)-1) = 0
This gives cos(x) = +/- 1 -> x = multiples of

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