
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 two points A(0, 2) and B(-4, 0) in the Cartesian coordinate system, M is the midpoint of AB. Establish a polar coordinate system with the origin as the pole and the positive x-axis as the polar axis. Then, the polar coordinates of M are _____________ (express the angle using the inverse trigonometric function).

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