
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 $\tan\alpha= \frac {4}{3}$, $\cos(\beta-\alpha)= \frac { \sqrt {2}}{10}$,  
(1) Find the value of $\sin^2\alpha-\sin\alpha\cos\alpha$  
(2) If $0<\alpha< \frac {\pi}{2}<\beta<\pi$, find the value of $\beta$.

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