
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 vectors $\overrightarrow{a}=(\cos α,\sin α)$ and $\overrightarrow{b}=(-2,2)$.
(1) If $\overrightarrow{a}\cdot \overrightarrow{b}= \frac {14}{5}$, find the value of $(\sin α+\cos α)^{2}$;
(2) If $\overrightarrow{a}$ is parallel to $\overrightarrow{b}$, find the value of $\sin (π-α)\cdot\sin ( \frac {π}{2}+α)$.

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