Find the limit of ln (sinx) as x approaches pi

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    Limit Ln Pi
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Homework Help Overview

The discussion revolves around finding the limit of ln(sin(x)) as x approaches π from the left. The subject area involves limits and properties of logarithmic and trigonometric functions.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants explore the application of the squeeze theorem and question how to set it up correctly. There are discussions about the behavior of sin(x) as x approaches π from the left and its implications for the natural logarithm.

Discussion Status

Some participants have suggested that the limit can be approached by considering the behavior of sin(x) as it approaches zero, while others have noted the need to clarify the method being used. There is an acknowledgment that the situation may not require the squeeze theorem as initially thought.

Contextual Notes

Participants mention that the teacher does not require the use of the delta/epsilon method, which influences their approach to the problem. There is also a focus on the behavior of sin(x) near π, which is critical to understanding the limit of ln(sin(x)).

essedbl
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I need to find the limit of. Ln (sinx) as x approaches pi-, that is, as x approaches pi from the left.

I thought I should use the squeeze theorem, but I am not sure how to apply it. My teacher is not requiring us to use the delta/Epsilon method, so I am sure it is a squeeze method. But how do I set it up?

I tried -1 < sinx < 1,
Thus ln (-1) < ln (sinx) < ln (1)

But you can't take the ln of a negative... please help.
 
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What can you say about \sin(x) as x \rightarrow \pi^-? Is it positive or negative? What value does it approach?
 
As x aproaches pi from the left your sine function aproaches 0. This means this is equivalent of finding the limit as the thing inside the natural log aproaches 0. Its very easy limit.
 
Last edited:
Oh. So this isn't squeeze action... I just find the limit of ln as sinx approaches zero. Hmm... I would need to graph that. But that should be simple enough. Tjanks guys
 
essedbl said:
Oh. So this isn't squeeze action... I just find the limit of ln as sinx approaches zero. Hmm... I would need to graph that.
Good idea. Remember that x is approaching π from the left, which says something about how sin(x) is approaching zero, and finally, what ln(sin(x)) is doing.
essedbl said:
But that should be simple enough. Tjanks guys
 

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