
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
The graph of the function $f(x)=A\cos x (A\neq 0)$ is shifted to the right by $\varphi$ units (where $0 < \varphi < \pi$) to obtain the curve $C$. If the tangent line equation of $C$ at $x=0$ is $y=x+\sqrt{3}$, then the equation of a symmetry axis of curve $C$ is ______.

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