
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 $\cos \alpha =-\dfrac{3}{4}, \sin \beta =\dfrac{2}{3}$, with $\alpha$ in the third quadrant and $\beta \in (\dfrac{\pi }{2}, \pi )$.

(I) Find the value of $\sin 2\alpha$;

(II) Find the value of $\cos (2\alpha + \beta )$.

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