
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 $\tan \alpha=2$, $\sin \beta= \frac {3}{5}$, $\beta\in\left( \frac {\pi}{2},\pi\right)$.  
(Ⅰ) Find the values of $\cos \beta$ and $\tan 2\alpha$  
(Ⅱ) Find the value of $\tan (2\alpha-\beta)$.

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