Math Problem Statement

lim x–0 sin(8x)/sin(9x)

Solution

To solve the limit:

limx0sin(8x)sin(9x)\lim_{x \to 0} \frac{\sin(8x)}{\sin(9x)}

We can use the small-angle approximation for sine, which states that sin(x)x\sin(x) \approx x as xx approaches 0. Applying this approximation to both sin(8x)\sin(8x) and sin(9x)\sin(9x):

limx0sin(8x)sin(9x)limx08x9x=89\lim_{x \to 0} \frac{\sin(8x)}{\sin(9x)} \approx \lim_{x \to 0} \frac{8x}{9x} = \frac{8}{9}

Thus, the limit is:

limx0sin(8x)sin(9x)=89\lim_{x \to 0} \frac{\sin(8x)}{\sin(9x)} = \frac{8}{9}

Would you like more details or have any questions?

Here are 5 related questions to explore this concept further:

  1. How would the result change if we had limx0sin(5x)sin(3x)\lim_{x \to 0} \frac{\sin(5x)}{\sin(3x)}?
  2. Can you use L'Hopital's Rule to verify the result?
  3. How does the small-angle approximation work, and when can it be used?
  4. What would happen if we took the limit of sin(kx)sin(mx)\frac{\sin(kx)}{\sin(mx)} as x0x \to 0 for any constants kk and mm?
  5. What is the limit of limx0tan(8x)tan(9x)\lim_{x \to 0} \frac{\tan(8x)}{\tan(9x)}?

Tip: The small-angle approximation is useful for simplifying trigonometric limits as x0x \to 0, especially when sine or tangent functions are involved.

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Math Problem Analysis

Mathematical Concepts

Limits
Trigonometry
Small-angle approximation

Formulas

Small-angle approximation: sin(x) ≈ x as x → 0
Limit: lim x→0 sin(8x)/sin(9x) ≈ lim x→0 (8x)/(9x) = 8/9

Theorems

Small-angle approximation
Limit of sine function as x approaches zero

Suitable Grade Level

Grades 10-12