
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 an acute triangle $ABC$ with angles $A$, $B$, $C$ opposite to sides $a$, $b$, $c$ respectively, it satisfies $\sqrt{\frac{1-\cos 2C}{2}} + \sin(B-A) = 2\sin 2A$.
- (I) Find $\frac{a}{b}$;
- (II) If $AB$ is the longest side, find the range of $\cos C$.

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