Math Problem Statement

lim_{x → 0} sin(8x) / tan(2x)

Solution

To solve the limit:

limx0sin(8x)tan(2x)\lim_{x \to 0} \frac{\sin(8x)}{\tan(2x)}

We can use the small-angle approximation for sine and tangent, which states that as x0x \to 0,

sin(x)xandtan(x)x.\sin(x) \approx x \quad \text{and} \quad \tan(x) \approx x.

Let's break it down step-by-step:

  1. The given limit is:

limx0sin(8x)tan(2x).\lim_{x \to 0} \frac{\sin(8x)}{\tan(2x)}.

  1. Applying the small-angle approximations:

sin(8x)8xandtan(2x)2xasx0.\sin(8x) \approx 8x \quad \text{and} \quad \tan(2x) \approx 2x \quad \text{as} \quad x \to 0.

  1. Substituting these approximations into the original expression:

limx08x2x.\lim_{x \to 0} \frac{8x}{2x}.

  1. Simplifying the expression:

limx08x2x=limx04=4.\lim_{x \to 0} \frac{8x}{2x} = \lim_{x \to 0} 4 = 4.

Thus, the value of the limit is:

4.\boxed{4}.

Would you like more details on any of these steps or have further questions?

Here are five related questions to expand on this topic:

  1. What happens if you substitute other values of xx in the limit equation?
  2. How does L'Hopital's Rule apply to solving limits like this?
  3. Can the small-angle approximations be used for larger values of xx?
  4. What is the geometric interpretation of the small-angle approximation for sine and tangent?
  5. How does the limit change if you replace the functions with their hyperbolic counterparts, like sinh(x)\sinh(x) and tanh(x)\tanh(x)?

Tip: When solving limits involving trigonometric functions near zero, small-angle approximations are a powerful tool for simplifying expressions.

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Math Problem Analysis

Mathematical Concepts

Limits
Trigonometric Functions
Small-Angle Approximation

Formulas

sin(x) ≈ x as x → 0
tan(x) ≈ x as x → 0

Theorems

Small-Angle Approximation
Limit Laws

Suitable Grade Level

Grades 11-12 (High School Calculus)