Math Problem Statement

решить

Solve the limit \(\lim_{x \to 0} \frac{\sin(3x)}{\tan\left(\frac{x}{2}\right)}\).

Solution

The given problem is:
limx0sin(3x)tan(x2)\lim_{x \to 0} \frac{\sin(3x)}{\tan\left(\frac{x}{2}\right)}

Step-by-step Solution:

  1. Expand the trigonometric functions around x=0x = 0:

    • The Taylor expansion for sin(3x)\sin(3x) around x=0x = 0 is: \sin(3x) \approx 3x \quad \text{(since \sin(x) \sim xforsmallfor smallx)}.
    • For tan(x2)\tan\left(\frac{x}{2}\right): \tan\left(\frac{x}{2}\right) \approx \frac{x}{2} \quad \text{(since \tan(x) \sim xforsmallfor smallx)}.
  2. Simplify the fraction: Substitute the approximations: sin(3x)tan(x2)3xx2.\frac{\sin(3x)}{\tan\left(\frac{x}{2}\right)} \approx \frac{3x}{\frac{x}{2}}.

  3. Simplify further: 3xx2=3x2x=6.\frac{3x}{\frac{x}{2}} = \frac{3x \cdot 2}{x} = 6.

  4. Final result: limx0sin(3x)tan(x2)=6.\lim_{x \to 0} \frac{\sin(3x)}{\tan\left(\frac{x}{2}\right)} = 6.


Would you like a detailed explanation of the Taylor expansions or other approaches?

Here are 5 related questions to explore further:

  1. What are the steps to derive Taylor series expansions for trigonometric functions?
  2. How does the small-angle approximation apply to sin(x)\sin(x) and tan(x)\tan(x)?
  3. How do limits involving trigonometric functions differ when higher-order terms are considered?
  4. How would this limit change if tan(x)\tan(x) or sin(x)\sin(x) were replaced with other trigonometric functions?
  5. How can L’Hôpital’s Rule be used to solve this limit instead of Taylor expansions?

Tip: When solving limits with trigonometric functions, always consider whether small-angle approximations or L’Hôpital’s Rule is more efficient!

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Math Problem Analysis

Mathematical Concepts

Limits
Trigonometry
Small-angle approximations

Formulas

\(\sin(x) \sim x\) for small \(x\)
\(\tan(x) \sim x\) for small \(x\)

Theorems

Limit theorem
Small-angle approximation theorem

Suitable Grade Level

Grades 10-12