Math Problem Statement

using lagrange interpolation formula find sin π/3 id the function y= sin x and x:0,π/4,π/2 and sinx:6,0.7071,1

Solution

We are asked to use Lagrange interpolation to approximate sin(π/3)\sin(\pi/3), given the function y=sin(x)y = \sin(x) with three data points:

  • x0=0x_0 = 0, y0=sin(0)=0y_0 = \sin(0) = 0
  • x1=π4x_1 = \frac{\pi}{4}, y1=sin(π4)=0.7071y_1 = \sin\left(\frac{\pi}{4}\right) = 0.7071
  • x2=π2x_2 = \frac{\pi}{2}, y2=sin(π2)=1y_2 = \sin\left(\frac{\pi}{2}\right) = 1

The Lagrange interpolation formula is:

L(x)=i=0nyij=0,jinxxjxixjL(x) = \sum_{i=0}^{n} y_i \prod_{j=0, j\neq i}^{n} \frac{x - x_j}{x_i - x_j}

For n=2n = 2 (since we have 3 points), the formula becomes:

L(x)=y0(xx1)(xx2)(x0x1)(x0x2)+y1(xx0)(xx2)(x1x0)(x1x2)+y2(xx0)(xx1)(x2x0)(x2x1)L(x) = y_0 \frac{(x - x_1)(x - x_2)}{(x_0 - x_1)(x_0 - x_2)} + y_1 \frac{(x - x_0)(x - x_2)}{(x_1 - x_0)(x_1 - x_2)} + y_2 \frac{(x - x_0)(x - x_1)}{(x_2 - x_0)(x_2 - x_1)}

Substitute the values of x0=0x_0 = 0, x1=π4x_1 = \frac{\pi}{4}, and x2=π2x_2 = \frac{\pi}{2}, along with their corresponding yy-values:

+ 0.7071 \cdot \frac{(x - 0)(x - \frac{\pi}{2})}{(\frac{\pi}{4} - 0)(\frac{\pi}{4} - \frac{\pi}{2})} + 1 \cdot \frac{(x - 0)(x - \frac{\pi}{4})}{(\frac{\pi}{2} - 0)(\frac{\pi}{2} - \frac{\pi}{4})}$$ Now, let's evaluate this at $$x = \frac{\pi}{3}$$. I'll calculate this step by step for you.Using Lagrange interpolation, the value of $$\sin\left(\frac{\pi}{3}\right)$$ is approximately $$0.8508$$. Would you like further details on the process or have any questions? Here are five related questions to explore: 1. How does Lagrange interpolation differ from Newton interpolation? 2. Can Lagrange interpolation be used for non-equally spaced data points? 3. What are the limitations of Lagrange interpolation in approximating functions? 4. How does increasing the number of data points affect the accuracy of interpolation? 5. Can Lagrange interpolation be applied to multidimensional data? **Tip:** Lagrange interpolation works best for a small number of points. For larger datasets, spline interpolation or other methods might be more efficient and accurate.

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Math Problem Analysis

Mathematical Concepts

Interpolation
Lagrange Interpolation
Trigonometry

Formulas

Lagrange interpolation formula: L(x) = Σ(y_i * Π((x - x_j) / (x_i - x_j))), where i ≠ j
Sine function: sin(x)

Theorems

Lagrange Polynomial Interpolation Theorem

Suitable Grade Level

Undergraduate