
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 the function $f(x)$ is an even function defined on $R$, and when $x\geqslant 0$, $f(x)={\left( \frac{1}{2}\right)}^{x}$.

(1) Find the value of $f(-1)$.
(2) Find the value domain $A$ of the function $f(x)$.

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