
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given the function $f(x)=\cos (2x- \frac {2π}{3})-\cos 2x (x\in R)$
(1) Find the period and minimum value of the function $f(x)$;
(2) In $\triangle ABC$, the sides opposite to angles $A$, $B$, $C$ are $a$, $b$, $c$ respectively. If $f(\frac {B}{2})=- \frac {\sqrt {3}}{2}$, $b=1$, $c= \sqrt {3}$, and $a > b$, find angles $B$ and $C$.

Present the answer in LaTex format: \boxed{Your answer}
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