
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 the Cartesian coordinate system $xOy$, consider the curve $\begin{cases} x=a\cos\varphi \\ y=b\sin\varphi \end{cases}$ ($a > b > 0$, $\varphi$ is the parameter, $0 \leq \varphi < 2\pi$). Two points $A$ and $B$ on the curve correspond to parameters $\alpha$ and $\alpha+ \frac{\pi}{2}$, respectively.  
(1) Find the general equation of the trajectory of the midpoint $M$ of the segment $AB$.  
(2) Determine the maximum and minimum values of the distance from the origin $O$ to the line $AB$.

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