
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
There is a point $A(2,0)$ and a point $C(\cos α, \sin α)$ on a plane, where $α \in (0, π)$. Point $O$ is the origin of the coordinate system and $| \overrightarrow{OA} + \overrightarrow{OC}| = \sqrt{7}$.
(1) Find the value of $α$;
(2) Find the angle between vectors $\overrightarrow{OA}$ and $\overrightarrow{AC}$.

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