# Solve #cos^3x=cosx#?

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#Cos^3x=cosx# I get got the #0, pi/2, pi# but I cant get #(3pi)/2# . If anyone can help out I would really appreciate it.

##### 2 Answers

Feb 10, 2018

See below

#### Explanation:

It's a little tricky, but try setting the equation = 0

Now factor out

And now factor the difference of two squares

Set each factor equal to 0 and solve using your unit circle

1)

2)

3)

Feb 11, 2018

See below.

#### Explanation:

Pythagorean identity: