
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
(1) Given $\frac{\sin\alpha + 3\cos\alpha}{3\cos\alpha - \sin\alpha} = 5$, find the value of $\sin^2\alpha - \sin\alpha\cos\alpha$.
(2) Given a point $P(-4, 3)$ on the terminal side of angle $\alpha$, determine the value of $\frac{\cos\left(\frac{\pi}{2} + \alpha\right)\sin\left(-\pi - \alpha\right)}{\cos\left(\frac{11\pi}{2} - \alpha\right)\sin\left(\frac{9\pi}{2} + \alpha\right)}$.

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