How to Solve the Limit of a Trigonometric Function?

In summary, we can use L'Hospital's rule to solve this limit and simplify it to get a final answer of 3.
  • #1
tmt1
234
0
I have this problem:

$\lim_{{t}\to{0}} \frac{tan(6t)}{sin2t}$

I know sin2t = 0 when t = 0, which means the original fraction is indeterminate, so how can apply the rules for limits to solve this limit?
 
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  • #2
hello there! do you know how to use L'Hospitals rule? i recommend you start with that. you can then easily simplify what you get from that (becomes extremely straight forward and simple after this) and then just take the limit of the top and bottom as x goes to 0.
 
  • #3
Hello, tmt!

We know that: .$\displaystyle\lim_{x\to0}\frac{\sin x}{x} \,=\,1$


$\displaystyle \lim_{t\to0} \frac{\tan(6t)}{\sin(2t)}$

$\displaystyle \frac{\tan(6t)}{\sin(2t)} \;=\;\frac{\frac{\sin(6t)}{\cos(6t)}}{\sin(2t)} \;=\;\frac{\sin(6t)}{\sin(2t)\cos(6t)}\;=\; \frac{\frac{6t}{6t}\cdot\sin(6t)}{\frac{2t}{2t}\cdot\sin(2t)\cos(6t)} $

$\displaystyle\qquad=\;\frac{6t\cdot\frac{\sin(6t)}{6t}}{2t\cdot\frac{\sin(2t)}{2t}}\;=\; 3\cdot\frac{\frac{\sin(6t)}{6t}}{\frac{\sin(2t)}{2t}\cdot\cos(6t)} $$\displaystyle \lim_{t\to0}\left( 3\cdot\frac{\frac{\sin(6t)}{6t}}{\frac{\sin(2t)}{2t}\cdot\cos(6t)}\right) \;=\; 3\cdot\frac{\lim \frac{\sin(6t)}{6t}}{\lim\frac{\sin(2t)}{2t}\cdot \lim\cos(6t)} \;=\;3\cdot\frac{1}{1\cdot1} \;=\;3$

 

FAQ: How to Solve the Limit of a Trigonometric Function?

What is the definition of the limit of a trigonometric function?

The limit of a trigonometric function is the value that a function approaches as its input approaches a certain value. It is a fundamental concept in calculus that helps determine the behavior of a function near a specific point.

How do you find the limit of a trigonometric function?

The limit of a trigonometric function can be found by evaluating the function at the point in question and observing the behavior of the function as the input approaches that point. If the function approaches a specific value, then that value is the limit. If the function oscillates or becomes undefined, then the limit does not exist.

What is the difference between a one-sided limit and a two-sided limit for a trigonometric function?

A one-sided limit is the value that a function approaches as its input approaches a certain value from only one side (either from the left or right). A two-sided limit is the value that a function approaches as its input approaches a certain value from both the left and right sides. In some cases, these two values may be different, indicating that the limit does not exist.

When does the limit of a trigonometric function not exist?

The limit of a trigonometric function does not exist when the function oscillates or becomes undefined as the input approaches a certain value. This can happen when the function has a vertical asymptote or when the input approaches a point where the function is undefined (such as when dividing by 0).

How can the limit of a trigonometric function be used in real-world applications?

The concept of a limit and its applications in trigonometry are used in various fields such as physics, engineering, and economics. For example, in physics, the velocity of an object can be determined by finding the limit of its position function as time approaches a certain value. In engineering, the limit can be used to analyze the stability and behavior of structures. In economics, limits can be used to study the behavior of supply and demand functions.

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