
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 a function $f(α) = \frac {\cos ( \frac {π}{2}+α)\cdot \cos (2π-α)\cdot \sin (-α+ \frac {3π}{2})}{\sin (-π-α)\cdot \sin ( \frac {3π}{2}+α)}$.
1. Simplify $f(α)$;
2. If $α$ is an angle in the third quadrant and $\cos (α- \frac {3π}{2})= \frac {1}{5}$, find the value of $f(α)$.

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