Math Problem Statement

lim x -> 0 (sin(1/2 * pi + x) - sin(x))/x

Solution

To solve the limit

limx0sin(π2+x)sin(x)x\lim_{x \to 0} \frac{\sin\left(\frac{\pi}{2} + x\right) - \sin(x)}{x}

we'll start by using the trigonometric identity for the sine of a sum:

sin(π2+x)=sin(π2)cos(x)+cos(π2)sin(x)\sin\left(\frac{\pi}{2} + x\right) = \sin\left(\frac{\pi}{2}\right)\cos(x) + \cos\left(\frac{\pi}{2}\right)\sin(x)

Since sin(π2)=1\sin\left(\frac{\pi}{2}\right) = 1 and cos(π2)=0\cos\left(\frac{\pi}{2}\right) = 0, the expression simplifies to:

sin(π2+x)=cos(x)\sin\left(\frac{\pi}{2} + x\right) = \cos(x)

Thus, the original limit becomes:

limx0cos(x)sin(x)x\lim_{x \to 0} \frac{\cos(x) - \sin(x)}{x}

To resolve the indeterminate form 00\frac{0}{0} as x0x \to 0, we use L'Hôpital's Rule. According to the rule:

limx0cos(x)sin(x)x=limx0sin(x)cos(x)1\lim_{x \to 0} \frac{\cos(x) - \sin(x)}{x} = \lim_{x \to 0} \frac{-\sin(x) - \cos(x)}{1}

Evaluating at x=0x = 0:

sin(0)cos(0)=01=1-\sin(0) - \cos(0) = -0 - 1 = -1

Thus, the limit is:

1\boxed{-1}

Would you like to explore more about this problem or any related topics?

Here are some related questions to think about:

  1. What are other applications of L'Hôpital's Rule?
  2. How does the Taylor series approximation help in evaluating limits?
  3. What is the geometric interpretation of

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Math Problem Analysis

Mathematical Concepts

Limits
Trigonometry

Formulas

Sine of a sum identity
L'Hôpital's Rule

Theorems

L'Hôpital's Rule

Suitable Grade Level

Advanced High School