Evaluate Sin2x dx

Calculus: Early Transcendentals
8th Edition
ISBN:9781285741550
Author:James Stewart
Publisher:James Stewart
Chapter1: Functions And Models
Section: Chapter Questions
Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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**Problem Statement**
Evaluate the integral: 

\[ \int_{0}^{\frac{\pi}{4}} \frac{\sin 2x}{1 + \cos^2 2x} \, dx \]

In this problem, we are asked to evaluate the definite integral of the function \(\frac{\sin 2x}{1 + \cos^2 2x}\) from 0 to \(\frac{\pi}{4}\).

**Detailed Steps and Explanation**

1. **Integral Setup**

   The integral is given by:

   \[ \int_{0}^{\frac{\pi}{4}} \frac{\sin 2x}{1 + \cos^2 2x} \, dx \]

2. **Substitution Method**

   One common approach to solving integrals involving trigonometric functions is using trigonometric identities and substitutions. In this case, consider the substitution \( u = 2x \).

   \[\text{If} \quad u = 2x, \quad \text{then} \quad du = 2 \, dx \quad \Rightarrow \quad dx = \frac{1}{2} \, du.\]

   The limits of integration change accordingly:

   \[ \text{When} \quad x = 0, \quad u = 2 \times 0 = 0.\]

   \[ \text{When} \quad x = \frac{\pi}{4}, \quad u = 2 \times \frac{\pi}{4} = \frac{\pi}{2}.\]

   Under this substitution, the integral becomes:

   \[ \int_{0}^{\frac{\pi}{2}} \frac{\sin u}{1 + \cos^2 u} \cdot \frac{1}{2} \, du \]

   Simplify the constant factor:

   \[ \frac{1}{2} \int_{0}^{\frac{\pi}{2}} \frac{\sin u}{1 + \cos^2 u} \, du \]

3. **Solving the Integral**

   At this stage, we apply further integration techniques such as partial fractions, further substitutions, or using standard integral tables to evaluate:

   Since deriving the exact integral involves specific steps tailored to the function, the general process involves recognizing the form and applying standard methods.

4. **Solution**

   After solving, we summarize
Transcribed Image Text:**Problem Statement** Evaluate the integral: \[ \int_{0}^{\frac{\pi}{4}} \frac{\sin 2x}{1 + \cos^2 2x} \, dx \] In this problem, we are asked to evaluate the definite integral of the function \(\frac{\sin 2x}{1 + \cos^2 2x}\) from 0 to \(\frac{\pi}{4}\). **Detailed Steps and Explanation** 1. **Integral Setup** The integral is given by: \[ \int_{0}^{\frac{\pi}{4}} \frac{\sin 2x}{1 + \cos^2 2x} \, dx \] 2. **Substitution Method** One common approach to solving integrals involving trigonometric functions is using trigonometric identities and substitutions. In this case, consider the substitution \( u = 2x \). \[\text{If} \quad u = 2x, \quad \text{then} \quad du = 2 \, dx \quad \Rightarrow \quad dx = \frac{1}{2} \, du.\] The limits of integration change accordingly: \[ \text{When} \quad x = 0, \quad u = 2 \times 0 = 0.\] \[ \text{When} \quad x = \frac{\pi}{4}, \quad u = 2 \times \frac{\pi}{4} = \frac{\pi}{2}.\] Under this substitution, the integral becomes: \[ \int_{0}^{\frac{\pi}{2}} \frac{\sin u}{1 + \cos^2 u} \cdot \frac{1}{2} \, du \] Simplify the constant factor: \[ \frac{1}{2} \int_{0}^{\frac{\pi}{2}} \frac{\sin u}{1 + \cos^2 u} \, du \] 3. **Solving the Integral** At this stage, we apply further integration techniques such as partial fractions, further substitutions, or using standard integral tables to evaluate: Since deriving the exact integral involves specific steps tailored to the function, the general process involves recognizing the form and applying standard methods. 4. **Solution** After solving, we summarize
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