Math Problem Statement

taylor series: f(x)=sinx, cenetered at a=pi

Solution

To find the Taylor series for f(x)=sin(x)f(x) = \sin(x) centered at a=πa = \pi, we use the formula for the Taylor series:

f(x)=f(a)+f(a)(xa)+f(a)2!(xa)2+f(a)3!(xa)3+f(x) = f(a) + f'(a)(x - a) + \frac{f''(a)}{2!}(x - a)^2 + \frac{f'''(a)}{3!}(x - a)^3 + \cdots

First, we calculate the derivatives of f(x)=sin(x)f(x) = \sin(x):

  1. f(x)=sin(x)f(x) = \sin(x)
  2. f(x)=cos(x)f'(x) = \cos(x)
  3. f(x)=sin(x)f''(x) = -\sin(x)
  4. f(x)=cos(x)f'''(x) = -\cos(x)
  5. f(4)(x)=sin(x)f^{(4)}(x) = \sin(x) (and the cycle repeats)

Next, evaluate these at x=πx = \pi:

  • f(π)=sin(π)=0f(\pi) = \sin(\pi) = 0
  • f(π)=cos(π)=1f'(\pi) = \cos(\pi) = -1
  • f(π)=sin(π)=0f''(\pi) = -\sin(\pi) = 0
  • f(π)=cos(π)=1f'''(\pi) = -\cos(\pi) = 1
  • f(4)(π)=sin(π)=0f^{(4)}(\pi) = \sin(\pi) = 0

Now substitute into the Taylor series:

f(x)=0+(1)(xπ)+02!(xπ)2+13!(xπ)3+0+f(x) = 0 + (-1)(x - \pi) + \frac{0}{2!}(x - \pi)^2 + \frac{1}{3!}(x - \pi)^3 + 0 + \cdots

Thus, the Taylor series simplifies to:

f(x)=(xπ)+16(xπ)3+f(x) = - (x - \pi) + \frac{1}{6}(x - \pi)^3 + \cdots

The general form for the series, accounting for the periodicity of sine, is:

sin(x)=(xπ)+16(xπ)31120(xπ)5+\sin(x) = - (x - \pi) + \frac{1}{6}(x - \pi)^3 - \frac{1}{120}(x - \pi)^5 + \cdots

Summary: The Taylor series for sin(x)\sin(x) centered at π\pi is:

sin(x)=(xπ)+(xπ)36(xπ)5120+\sin(x) = - (x - \pi) + \frac{(x - \pi)^3}{6} - \frac{(x - \pi)^5}{120} + \cdots

Would you like more details on any part of this derivation, or do you have any specific questions? Here are some related questions to consider:

  1. How does the Taylor series converge for sin(x)\sin(x)?
  2. Can you derive the Taylor series for cos(x)\cos(x) centered at π\pi?
  3. What is the radius of convergence for the Taylor series of sin(x)\sin(x)?
  4. How does the Taylor series for sin(x)\sin(x) compare to its Maclaurin series?
  5. Can you apply this series to approximate sin(π+x)\sin(\pi + x) for small xx?

Tip: When working with Taylor series, always check the derivatives at the center point for a clear understanding of the series' behavior.

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Math Problem Analysis

Mathematical Concepts

Calculus
Taylor Series
Trigonometric Functions

Formulas

Taylor series formula: f(x) = f(a) + f'(a)(x - a) + f''(a)/2!(x - a)^2 + ...

Theorems

Taylor's theorem

Suitable Grade Level

Grades 11-12