
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
Let the tangent line at any point on the curve $f(x)=-e^{x}-x$ (where $e$ is the base of the natural logarithm) be $l_{1}$. There always exists a tangent line $l_{2}$ at some point on the curve $g(x)=ax+2\cos x$ such that $l_{1} \bot l_{2}$. Find the range of the real number $a$.

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