
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
Point $A$ starts from $(1,0)$ and moves counterclockwise along the unit circle to point $B$. If the coordinates of point $B$ are $\left(- \frac {3}{5}, \frac {4}{5}\right)$, and let $\angle AOB=\alpha$, then $\sin 2\alpha=$ ______.

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