Math Problem Statement

prove that tan(x)/x = 1

Solution

To prove that tan(x)x=1\frac{\tan(x)}{x} = 1, we need to examine the statement more closely.

Step 1: Understanding the claim

The equation tan(x)x=1\frac{\tan(x)}{x} = 1 suggests that tan(x)=x\tan(x) = x. This is not true in general for all values of xx. In fact, tan(x)\tan(x) and xx are different functions, and they do not satisfy this equation universally.

However, this equation holds approximately when xx approaches 0. In other words, the limit of tan(x)x\frac{\tan(x)}{x} as x0x \to 0 is 1. Let's prove this.

Step 2: Use of Limit

We aim to prove:

limx0tan(x)x=1\lim_{x \to 0} \frac{\tan(x)}{x} = 1

To do this, we can apply L'Hôpital's Rule or use the Taylor expansion of tan(x)\tan(x) around x=0x = 0.

Step 3: Taylor Expansion of tan(x)\tan(x)

The Taylor series expansion of tan(x)\tan(x) around x=0x = 0 is:

tan(x)=x+x33+O(x5)\tan(x) = x + \frac{x^3}{3} + O(x^5)

For small values of xx, we can approximate tan(x)\tan(x) as:

tan(x)x\tan(x) \approx x

Step 4: Applying the Approximation

Using this approximation:

tan(x)xxx=1\frac{\tan(x)}{x} \approx \frac{x}{x} = 1

Thus, as x0x \to 0, tan(x)x1\frac{\tan(x)}{x} \to 1.

Step 5: Conclusion

We have shown that:

limx0tan(x)x=1\lim_{x \to 0} \frac{\tan(x)}{x} = 1

This means the original statement tan(x)x=1\frac{\tan(x)}{x} = 1 is approximately true for very small xx. However, it is not true for all values of xx.

Summary

The equation tan(x)x=1\frac{\tan(x)}{x} = 1 holds only in the limit as x0x \to 0. Otherwise, tan(x)\tan(x) and xx are different functions.


Do you have any questions or want more details on this? Here are five related questions you might find helpful:

  1. What are other trigonometric limits similar to limx0tan(x)x=1\lim_{x \to 0} \frac{\tan(x)}{x} = 1?
  2. How does L'Hôpital's Rule apply to solving limits like this?
  3. Can we derive the Taylor series expansion of tan(x)\tan(x) in more detail?
  4. How can we use small-angle approximations in trigonometry?
  5. What is the difference between tan(x)\tan(x) and other trigonometric functions when approaching 0?

Tip: Remember that many trigonometric identities and limits hold true only under specific conditions, such as near certain values like x=0x = 0.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Limits
Small-Angle Approximation

Formulas

lim(x→0) tan(x)/x = 1
Taylor series of tan(x)

Theorems

L'Hôpital's Rule
Taylor Series Expansion

Suitable Grade Level

Grades 11-12 (Pre-Calculus, Calculus)