/*! 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 8 Find the indicated limits. $$\... [FREE SOLUTION] | 91Ó°ÊÓ

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Find the indicated limits. $$\lim _{x \rightarrow 0} \frac{\sin x}{\sin ^{-1} x}$$

Short Answer

Expert verified
The limit of \(\frac{\sin x}{\sin ^{-1} x}\) as \(x\) approaches 0 is 1.

Step by step solution

01

Convert the Function Form

Use the equivalency \(\sin (\sin ^{-1} x) = x\) to convert the original function into \(\frac{\sin x}{x}\). This clears the inverse function in the denominator.
02

Apply L'Hopital's Rule

At this point you have \(\lim _{x \rightarrow 0} \frac{\sin x}{x}\) which is in the form of 0/0 when \(x = 0\). This is an indeterminate form and you can apply L'Hopital's rule. L'Hopital's rule states that \(\lim _{x \rightarrow a} \frac{f(x)}{g(x)} = \lim _{x \rightarrow a} \frac{f'(x)}{g'(x)}\) if \(\lim _{x \rightarrow a} f(x) = \lim _{x \rightarrow a} g(x) = 0\) or \(\pm \infty\). Differentiating the numerator produces \(\cos x\) and differentiating the denominator gives 1.
03

Evaluate the Limit

Now we have \(\lim _{x \rightarrow 0} \frac{\cos x}{1} = \cos 0\) according to the limit rule that if \(k\) is a constant and \(n\) is a positive integer, then \(\lim _{x \rightarrow a} k = k\) and \(\lim _{x \rightarrow a} x^n = a^n\), with \(a\) being in the domain of the function. The value of \(\cos 0\) is 1, so the limit of the original function as \(x\) approaches 0 is 1.

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Key Concepts

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

Inverse Trigonometric Functions
Inverse trigonometric functions are special functions that help reverse trigonometric operations. These include functions like \(\sin^{-1}x\), \(\cos^{-1}x\), and \(\tan^{-1}x\). For instance, \(\sin^{-1}x\) is the angle whose sine value is \(x\). They are useful for reversing computations where the value of a trigonometric ratio is known, and the measure of the associated angle is needed.

In our specific problem, we started with \(\frac{\sin x}{\sin^{-1} x}\). It's important to know that \(\sin(\sin^{-1}x) = x\) for values of \(x\) in the interval \([-1,1]\). This property simplifies our calculation by reducing the inverse trigonometric function to just \(x\) itself, making the problem easier to handle before applying other calculus tools.
L'Hopital's Rule
L'Hopital's Rule is a powerful method in calculus used to evaluate limits that result in indeterminate forms like 0/0 or \(\frac{\infty}{\infty}\). If a limit problem results in these forms after direct substitution, L'Hopital's Rule allows you to differentiate the numerator and the denominator separately and take the limit again.

In our example, after simplifying the function to \(\frac{\sin x}{x}\), we encounter the 0/0 form when \(x = 0\). This is where L’Hopital's Rule comes to the rescue. We differentiate the numerator, giving us \(\cos x\), and the denominator remains constant as 1. Thus, the limit now is \(\lim _{x \rightarrow 0} \frac{\cos x}{1} \). This method transforms a seemingly complicated limit into something more manageable.
Limit Evaluation
Limit evaluation is a fundamental concept in calculus used to find the value that a function approaches as the input approaches some value. Evaluating limits often involves substitution, simplification, or employing techniques like factoring, conjugation, or L'Hopital's Rule.

In the given problem, we needed to evaluate \(\lim _{x \rightarrow 0} \frac{\cos x}{1}\). By knowing basic trigonometric values, we find \(\cos 0 = 1\). Thus, the limit evaluates directly to 1. The ease of this final step in calculation demonstrates the power of correctly applying limit properties.
Indeterminate Forms
Indeterminate forms are expressions in mathematics that do not initially provide clear, evaluatable answers, like 0/0, \infty/\infty, or \(0 \times \infty\). These forms indicate a need for additional algebraic manipulation or calculus techniques to determine the actual limit value.

In the context of this problem, when substituting \(x = 0\) directly into \(\frac{\sin x}{x}\), it results in the indeterminate form 0/0. This is a classic situation where applying L'Hopital's Rule is appropriate to find a meaningful limit. Recognizing indeterminate forms is crucial in deciding the next steps for simplifying and accurately evaluating limits.

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