Finding domain of a trigonometric function

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SUMMARY

The domain of the function $$f(x) = \frac{1+x}{ e^{cos(x)}}$$ is all real numbers. The numerator, $$1+x$$, is defined for all x. The denominator, $$e^{cos(x)}$$, is always positive since both $$cos(x)$$ and $$e^x$$ are defined for all x, ensuring that the composition is also defined everywhere. Therefore, there are no restrictions on the domain, confirming that the function is defined for all real numbers.

PREREQUISITES
  • Understanding of trigonometric functions, specifically $$cos(x)$$.
  • Knowledge of exponential functions, particularly $$e^{x}$$.
  • Familiarity with the concept of function domains.
  • Basic algebraic manipulation skills.
NEXT STEPS
  • Study the properties of exponential functions and their behavior.
  • Explore the implications of trigonometric function compositions.
  • Learn about determining the domain of more complex functions.
  • Investigate limits and continuity in relation to function domains.
USEFUL FOR

Students studying calculus, mathematicians analyzing function behavior, and educators teaching function domains in mathematics.

tmt1
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I need to find the domain of this function:

$$f(x) = \frac{1+x}{ e^{cos(x)}}$$

I set $${ e^{cos(x)}}> 0$$

But I'm not sure what to do after this.
 
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tmt said:
I need to find the domain of this function:

$$f(x) = \frac{1+x}{ e^{cos(x)}}$$

I set $${ e^{cos(x)}}> 0$$

But I'm not sure what to do after this.

The top is obviously defined for all x.

The bottom, as you have established, is always positive. As both cos(x) and e^x are defined for all x, so is their composition.

So the top and bottom are defined for all x. The only place where the quotient of the two functions might not be defined is where the denominator is 0. But you already established that this doesn't happen anywhere.

So what is the domain of your function?
 
Prove It said:
The top is obviously defined for all x.

The bottom, as you have established, is always positive. As both cos(x) and e^x are defined for all x, so is their composition.

So the top and bottom are defined for all x. The only place where the quotient of the two functions might not be defined is where the denominator is 0. But you already established that this doesn't happen anywhere.

So what is the domain of your function?

All real numbers?
 
tmt said:
All real numbers?

Correct :)
 

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