
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 $\cos \left( \frac {π}{4}-α \right) = \frac {3}{5}$, and $\sin \left( \frac {5π}{4}+β \right) = - \frac {12}{13}$, with $α \in \left( \frac {π}{4}, \frac {3π}{4} \right)$ and $β \in (0, \frac {π}{4})$, find the value of $\sin (α+β)$.

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