/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 27 Find the limits. $$\lim _{\the... [FREE SOLUTION] | 91Ó°ÊÓ

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Find the limits. $$\lim _{\theta \rightarrow 0} \frac{\theta^{2}}{1-\cos \theta}$$

Short Answer

Expert verified
The limit is 2.

Step by step solution

01

Recognize the indeterminate form

First, substitute \(\theta = 0\) directly into the expression \(\frac{\theta^2}{1 - \cos \theta}\). This gives \(\frac{0^2}{1 - \cos 0} = \frac{0}{0}\), which is an indeterminate form. This means we need to use a mathematical technique to evaluate the limit.
02

Apply L'Hôpital's Rule

Since the limit is in the indeterminate form \(\frac{0}{0}\), apply L'Hôpital's Rule, which involves taking the derivatives of the numerator and the denominator. The derivative of the numerator \(\theta^2\) is \(2\theta\), and the derivative of the denominator \(1 - \cos \theta\) is \(\sin \theta\). Thus, the new limit is \(\lim_{\theta \rightarrow 0} \frac{2\theta}{\sin \theta}\).
03

Simplify the new expression

The new expression \(\frac{2\theta}{\sin \theta}\) can be simplified by recognizing a standard limit. It is known that \(\lim_{x \rightarrow 0} \frac{x}{\sin x} = 1\). Therefore, \(\lim_{\theta \rightarrow 0} \frac{2\theta}{\sin \theta} = 2\).
04

Conclusion

The limit \(\lim_{\theta \rightarrow 0} \frac{\theta^2}{1 - \cos \theta}\) simplifies to 2 after applying L'Hôpital's Rule and recognizing a standard trigonometric limit.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

L'Hôpital's Rule
When faced with challenging limits, especially those that present indeterminate forms like \( \frac{0}{0} \), a handy tool in calculus is L'Hôpital's Rule. This rule provides a way to simplify the evaluation of limits by differentiating the numerator and the denominator separately.To apply L'Hôpital's Rule, make sure:
  • The limit results in an indeterminate form, either \( \frac{0}{0} \) or \( \frac{\infty}{\infty} \).
  • The functions in the numerator and denominator are differentiable near the point of interest.
Once these conditions are met, you can replace the original expression with the limit of the derivatives without changing the limit’s value. This often leads to a simpler expression, making the problem much easier to solve.
Indeterminate Forms
Indeterminate forms occur when substituting a point into a limit leads to expressions like \( \frac{0}{0} \), \( \frac{\infty}{\infty} \), \( 0^{0} \), and others. These forms do not provide enough information to determine the limit directly, as the result can vary depending on additional context or manipulation.To tackle indeterminate forms, consider:
  • Identifying the type of indeterminate form present.
  • Applying rules and techniques like L'Hôpital's Rule, algebraic simplifications, or known limits to resolve the uncertainty.
By addressing these forms thoughtfully, you can transform an undefined expression into one that's manageable, revealing the true limit of the function.
Trigonometric Limits
Trigonometric limits are a crucial part of calculus, especially when dealing with limits involving trigonometric functions like sine, cosine, and tangent. There's a well-known limit principle for trigonometric functions that's frequently used to simplify expressions.Consider these important limits:
  • \( \lim_{x \rightarrow 0} \frac{\sin x}{x} = 1 \)
  • \( \lim_{x \rightarrow 0} \frac{1 - \cos x}{x^2} = \frac{1}{2} \)
These results help simplify complex trigonometric expressions by recognizing patterns and making substitutions more straightforward. In the context of the original exercise, knowing that \( \lim_{x \rightarrow 0} \frac{x}{\sin x} = 1 \) was pivotal in determining that the limit of the new expression was \( 2 \). Understanding and using these trigonometric limits can ease your path through calculus problems.

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Most popular questions from this chapter

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