Limit of a trigonometric function

In summary, the conversation revolves around finding limits, specifically the limits of x*sin(x), sin(x)/√x, and sin(x)/x as x approaches infinity or 0. The third limit is related to the first and second, and the hint given is that the product of a function that goes to 0 with a bounded function must have a limit of 0. However, in this case, neither function goes to 0 and it is uncertain if the function has an infinite limit due to its oscillating nature.
  • #1
Yankel
395
0
Hello all,

I need some guidance in solving these limits:

\[\lim_{x\rightarrow \infty }x\cdot sin(x)\]

\[\lim_{x\rightarrow 0 }\frac{sin(x)}{\sqrt{x}}\]

\[\lim_{x\rightarrow \infty }\frac{sin(x)}{x}\]

I guess that the second and third ones are somehow related to

\[\lim_{x\rightarrow 0 }\frac{sin(x)}{x}\]

But I am not sure how to convert the known limit into the new ones.

Thank you in advance.
 
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  • #2
Yankel said:
Hello all,

I need some guidance in solving these limits:

\[\lim_{x\rightarrow \infty }x\cdot sin(x)\]

\[\lim_{x\rightarrow 0 }\frac{sin(x)}{\sqrt{x}}\]

\[\lim_{x\rightarrow \infty }\frac{sin(x)}{x}\]

I guess that the second and third ones are somehow related to

\[\lim_{x\rightarrow 0 }\frac{sin(x)}{x}\]

But I am not sure how to convert the known limit into the new ones.

Thank you in advance.

Hint for the third: The product of a function that goes to 0 with a bounded function must have a limit of 0.
 
  • #3
I see. Can I use the same logic in the first as well ?
 
  • #4
Yankel said:
I see. Can I use the same logic in the first as well ?

No, neither function goes to 0.

As for whether the function has an infinite limit, as it oscillates I would lean towards no...
 

FAQ: Limit of a trigonometric function

What is the limit of a trigonometric function?

The limit of a trigonometric function is the value that the function approaches as the input value gets closer and closer to a specific value. It is a fundamental concept in calculus and is used to determine the behavior of a function near a given point.

How do you find the limit of a trigonometric function?

To find the limit of a trigonometric function, you can use various techniques such as direct substitution, factoring, or trigonometric identities. It is also important to know the properties and rules of limits, such as the limit laws, to solve for the limit of a trigonometric function.

What are the common trigonometric functions?

The most commonly used trigonometric functions are sine, cosine, tangent, cotangent, secant, and cosecant. These functions are used to relate the angles and sides of a right triangle and are essential in many mathematical and scientific applications.

Why is the limit of a trigonometric function important?

The limit of a trigonometric function is important because it helps us understand the behavior of a function near a specific value. It is also used to solve real-world problems and is a fundamental concept in calculus, which is the basis for many other branches of mathematics and science.

Can the limit of a trigonometric function be undefined?

Yes, the limit of a trigonometric function can be undefined if it does not exist or if it approaches different values from the left and right sides of the limit point. This is known as an "oscillating" or "discontinuous" limit and may occur when the function has vertical asymptotes or sharp turns near the limit point.

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