
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 $\alpha$ is an angle in the third quadrant, $f\left( \alpha \right)=\dfrac{\sin (\alpha -\dfrac{\pi }{2})\cos (\dfrac{3\pi }{2}+\alpha )\tan (\pi -\alpha )}{\tan (-\alpha -\pi )\sin (-\alpha -\pi )}$.

(1) Simplify $f\left( \alpha \right)$

(2) If $\cos (\alpha -\dfrac{3\pi }{2})=\dfrac{1}{5}$, find the value of $f\left( \alpha \right)$

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