
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, point $O$ is the origin, $A(1,2)$, $B(-3,4)$.  
(Ⅰ) Find the coordinates of vector $\overrightarrow{AB}$ and $|\overrightarrow{AB}|$;  
(Ⅱ) Find the cosine of the angle between vectors $\overrightarrow{OA}$ and $\overrightarrow{OB}$.

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