
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
In $\triangle ABC$, the sides opposite to angles $A$, $B$, and $C$ are respectively $a$, $b$, and $c$, and it is given that $\sqrt{3}a\cos C = (2b - \sqrt{3}c)\cos A$.  
$(1)$ Find the magnitude of angle $A$;  
$(2)$ Find the range of values for $\cos \left( \frac{5\pi}{2} - B \right) - 2\sin^2 \frac{C}{2}$.

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