
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 $f(x)=2\sin(x + \dfrac{\pi}{6}) - 2\cos x$, where $x\in\left[\dfrac{\pi}{2}, \pi\right]$:  
(1) If $\sin x = \dfrac{4}{5}$, find the value of $f(x)$.  
(2) Determine the range and the axis of symmetry of $f(x)$.

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