
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
Let O be the origin of coordinates, A(4, a), B(b, 8), C(a, b),
(Ⅰ) If quadrilateral OABC is a parallelogram, find the size of ∠AOC;
(Ⅱ) Under the condition of (Ⅰ), suppose the midpoint of AB is D, OD intersects AC at E, find the vector $$\overrightarrow {OE}$$.

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