
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 vectors $\overrightarrow{a}=(\sin x,\cos x)$, $\overrightarrow{b}=(\cos x,\sin x)$, where $x\in R$, and the function $f(x)= \overrightarrow{a}\cdot( \overrightarrow{a}- \overrightarrow{b})$.
(1) Find the smallest positive period of the function $f(x)$;
(2) When $x\in\left[-\frac{\pi}{4}, \frac{\pi}{4}\right]$, find the range of the function $f(x)$.

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