How do I solve the limit of tan^2(2x) / 3x^2 as x approaches 0?

In summary, the conversation discusses finding the limit of tan^2(2x) / 3x^2 as x approaches 0 and suggests using the substitution of sin(2x)/cos(2x) and the known limit of sin(x)/x as x approaches 0 to simplify the problem. It also mentions the use of L'Hopital's rule and provides a hint for solving the problem. Ultimately, the person asking for help is able to find their answer with the assistance of the conversation.
  • #1
theCandyman
398
2
I am completely lost on where to start, any help would be appreciated:

lim (x->0) tan^2(2x) / 3x^2

I do not have any work so far, but I'm trying to find a way to get rid of the x^2 in the denominator, which so far has been fruitless.
 
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  • #2
Try replacing tan(2x) with sin(2x)/cos(2x). You probably know something about the limit of sin(x)/x as x->0.
 
  • #3
theCandyman said:
I am completely lost on where to start, any help would be appreciated:

lim (x->0) tan^2(2x) / 3x^2

I do not have any work so far, but I'm trying to find a way to get rid of the x^2 in the denominator, which so far has been fruitless.

This limit works fine without the aid of Mr.L'Ho^pital.
Are u 100% convinced that:
[tex] \lim_{2x \rightarrow 0} \frac{\tan{2x}}{2x} =1 [/tex]
??

If so,u'll be able to apply the formula above properly and get the result.

One more hint:
[tex]\lim_{x \rightarrow 0} \frac{\tan^{2} 2x}{3x^2} = \frac{4}{3}
(\lim_{2x \rightarrow 0} \frac{\tan{2x}}{2x})^{2} [/tex]

I hope you can take it from there.
 
  • #4
Thank you both, I have my answer now.
 

1. What is a limit with a trig function?

A limit with a trig function is a mathematical concept that describes the behavior of a function as the input values approach a certain point. It is often used to determine the value of a function at a point where it is undefined or to analyze the behavior of a function at certain points.

2. How do you find the limit of a trig function?

The limit of a trig function can be found by evaluating the function at the point in question and also by analyzing the behavior of the function as the input values approach that point. This can be done using algebraic manipulation, graphing, or other mathematical methods.

3. Can a limit with a trig function have multiple values?

No, a limit with a trig function can only have one value. This value represents the behavior of the function at a specific point and cannot have multiple values.

4. What is the difference between a left-sided limit and a right-sided limit with a trig function?

A left-sided limit with a trig function describes the behavior of the function as the input values approach the point from the left side, while a right-sided limit describes the behavior from the right side. The difference between these two types of limits can sometimes result in different values.

5. How can limits with trig functions be used in real-life applications?

Limits with trig functions have many real-life applications, such as in physics, engineering, and economics. They can be used to analyze the behavior of systems and to predict the values of certain variables at specific points. For example, in physics, limits with trig functions can be used to determine the velocity of an object as it approaches a certain point in space.

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