
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 an acute triangle ABC with angles $A$, $B$, $C$ and opposite sides $a$, $b$, $c$, respectively, and $a=2b\sin A$:  
$(1)$ Find the size of angle $B$;  
$(2)$ Determine the range of values for $\cos A+\sin C$.

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