Sin 2B Cos2B 17. tan 2B = 289 289 %3D cos(a – B) = CosACosB+ SinA 18. %3D Sin2B=2Sin BCesB 17

Trigonometry (11th Edition)
11th Edition
ISBN:9780134217437
Author:Margaret L. Lial, John Hornsby, David I. Schneider, Callie Daniels
Publisher:Margaret L. Lial, John Hornsby, David I. Schneider, Callie Daniels
Chapter1: Trigonometric Functions
Section: Chapter Questions
Problem 1RE: 1. Give the measures of the complement and the supplement of an angle measuring 35°.
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Did I do 17 and 18 right?

Certainly! Here is the transcription and detailed explanation of the mathematical content in the image:

---

### Transcription of Mathematical Content

#### Problem 17
- Expression: \(\tan 2\beta = \frac{\sin 2B}{\cos 2B}\)
- Equation: \(\sin 2B = 2 \sin B \cos B\)

1. Simplification:
   \[
   2\left(\frac{\sqrt{5}}{3}\right) \left(\frac{2}{3}\right) = 2 \cdot \frac{2\sqrt{5}}{9}
   \]

2. Result: 
   \[
   \frac{4\sqrt{5}}{9}
   \]

#### Problem 18
- Expression: \(\cos(\alpha - \beta) = \cos A \cos B + \sin A \sin B\)

1. Calculation:
   \[
   \left(\frac{-15}{17}\right)\left(\frac{2}{3}\right) + \left(\frac{-8}{17}\right)\left(\frac{\sqrt{5}}{3}\right)
   \]
   \[
   = \frac{-30}{51} + \frac{-8\sqrt{5}}{51}
   \]

2. Combined Result:
   \[
   \frac{-30 - 8\sqrt{5}}{51}
   \]

3. Simplified Final Result:
   \[
   - \frac{30 + 8\sqrt{5}}{51}
   \]

### Explanation of Content

The content involves trigonometric identities and involved calculations:

1. **Trigonometric Identities**: 
   - The double angle identity for sine, \(\sin 2B = 2 \sin B \cos B\), is used to simplify expressions.
   - A formula for cosine of the difference of angles, \(\cos(\alpha - \beta)\), is used.

2. **Algebraic Manipulations**:
   - Fractional multiplication and simplification are prominent in the problem-solving process.
   - Radical expressions (\(\sqrt{5}\)) are involved, emphasizing the need for careful handling of irrational numbers.

This transcription should assist students in understanding the application of trigonometric identities and algebraic techniques in complex expressions.
Transcribed Image Text:Certainly! Here is the transcription and detailed explanation of the mathematical content in the image: --- ### Transcription of Mathematical Content #### Problem 17 - Expression: \(\tan 2\beta = \frac{\sin 2B}{\cos 2B}\) - Equation: \(\sin 2B = 2 \sin B \cos B\) 1. Simplification: \[ 2\left(\frac{\sqrt{5}}{3}\right) \left(\frac{2}{3}\right) = 2 \cdot \frac{2\sqrt{5}}{9} \] 2. Result: \[ \frac{4\sqrt{5}}{9} \] #### Problem 18 - Expression: \(\cos(\alpha - \beta) = \cos A \cos B + \sin A \sin B\) 1. Calculation: \[ \left(\frac{-15}{17}\right)\left(\frac{2}{3}\right) + \left(\frac{-8}{17}\right)\left(\frac{\sqrt{5}}{3}\right) \] \[ = \frac{-30}{51} + \frac{-8\sqrt{5}}{51} \] 2. Combined Result: \[ \frac{-30 - 8\sqrt{5}}{51} \] 3. Simplified Final Result: \[ - \frac{30 + 8\sqrt{5}}{51} \] ### Explanation of Content The content involves trigonometric identities and involved calculations: 1. **Trigonometric Identities**: - The double angle identity for sine, \(\sin 2B = 2 \sin B \cos B\), is used to simplify expressions. - A formula for cosine of the difference of angles, \(\cos(\alpha - \beta)\), is used. 2. **Algebraic Manipulations**: - Fractional multiplication and simplification are prominent in the problem-solving process. - Radical expressions (\(\sqrt{5}\)) are involved, emphasizing the need for careful handling of irrational numbers. This transcription should assist students in understanding the application of trigonometric identities and algebraic techniques in complex expressions.
The image contains a mathematical problem involving trigonometric identities and calculations. Below is a transcription and explanation suitable for an educational context:

### Given:
- \(\sin \alpha = -\frac{8}{17}\), with \(\pi \leq \alpha \leq \frac{3\pi}{2}\)
- \(\cos \beta = \frac{2}{3}\), with \(\frac{3\pi}{2} \leq \beta \leq 2\pi\)

### Problem:
1. **Calculate \(\cos \alpha\):**

   Using the identity: 
   \[
   \cos^2 \alpha = 1 - \sin^2 \alpha
   \]

   Substituting the given \(\sin \alpha\):
   \[
   \cos^2 \alpha + \left(-\frac{8}{17}\right)^2 = 1
   \]
   \[
   \cos^2 \alpha = 1 - \frac{64}{289}
   \]
   \[
   \cos^2 \alpha = \frac{225}{289}
   \]

   Taking the square root:
   \[
   \cos \alpha = \sqrt{\frac{225}{289}} = \frac{15}{17}
   \]

   Since \(\pi \leq \alpha \leq \frac{3\pi}{2}\), \(\cos \alpha\) is negative:
   \[
   \cos \alpha = -\frac{15}{17}
   \]

2. **Calculate \(\sin \beta\):**

   Using the identity:
   \[
   \sin \beta = \sqrt{1 - \cos^2 \beta}
   \]

   Substituting the given \(\cos \beta\):
   \[
   \sin^2 \beta = 1 - \left(\frac{2}{3}\right)^2
   \]
   \[
   \sin^2 \beta = 1 - \frac{4}{9}
   \]
   \[
   \sin^2 \beta = \frac{5}{9}
   \]

   Taking the square root:
   \[
   \sin \beta = \sqrt{\frac{5}{9}} = \frac{\sqrt{5}}{3}
   \]

   Since \(\
Transcribed Image Text:The image contains a mathematical problem involving trigonometric identities and calculations. Below is a transcription and explanation suitable for an educational context: ### Given: - \(\sin \alpha = -\frac{8}{17}\), with \(\pi \leq \alpha \leq \frac{3\pi}{2}\) - \(\cos \beta = \frac{2}{3}\), with \(\frac{3\pi}{2} \leq \beta \leq 2\pi\) ### Problem: 1. **Calculate \(\cos \alpha\):** Using the identity: \[ \cos^2 \alpha = 1 - \sin^2 \alpha \] Substituting the given \(\sin \alpha\): \[ \cos^2 \alpha + \left(-\frac{8}{17}\right)^2 = 1 \] \[ \cos^2 \alpha = 1 - \frac{64}{289} \] \[ \cos^2 \alpha = \frac{225}{289} \] Taking the square root: \[ \cos \alpha = \sqrt{\frac{225}{289}} = \frac{15}{17} \] Since \(\pi \leq \alpha \leq \frac{3\pi}{2}\), \(\cos \alpha\) is negative: \[ \cos \alpha = -\frac{15}{17} \] 2. **Calculate \(\sin \beta\):** Using the identity: \[ \sin \beta = \sqrt{1 - \cos^2 \beta} \] Substituting the given \(\cos \beta\): \[ \sin^2 \beta = 1 - \left(\frac{2}{3}\right)^2 \] \[ \sin^2 \beta = 1 - \frac{4}{9} \] \[ \sin^2 \beta = \frac{5}{9} \] Taking the square root: \[ \sin \beta = \sqrt{\frac{5}{9}} = \frac{\sqrt{5}}{3} \] Since \(\
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