
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 that $\overrightarrow {a}=(\cosα，\sinα)， \overrightarrow {b}=(\sinβ，\cosβ)，| \overrightarrow {a}- \overrightarrow {b}|= \frac {2 \sqrt {5}}{5}$

1. Find the value of $\sin({\alpha+β})$
2. If $0＜α＜ \frac {π}{2}，- \frac {π}{2}＜β＜0，\cosβ= \frac {12}{13}$, find the value of $\sinα$

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