4 If tan(a) and cos(b) 3 answer in a simplified fraction. 8 with a in quadrant III and b in quadrant II. Find sin(a + b) Leave you 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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**Problem:**

If \( \tan(a) = \frac{4}{3} \) and \( \cos(b) = -\frac{8}{17} \), with \( a \) in quadrant III and \( b \) in quadrant II, find \( \sin(a + b) \). Leave your answer in a simplified fraction.

**Explanation:**

To solve this problem, follow these steps:

1. **Find \(\sin(a)\) and \(\cos(a)\):**

   Since \(\tan(a) = \frac{4}{3}\), and \(a\) is in quadrant III:
   \[
   \sin(a) = -\frac{4}{5}, \quad \cos(a) = -\frac{3}{5}
   \]
   In quadrant III, both sine and cosine are negative.

2. **Find \(\sin(b)\):**

   Given \(\cos(b) = -\frac{8}{17}\) and \(b\) in quadrant II, where sine is positive and cosine is negative:
   \[
   \sin(b) = \frac{15}{17}
   \]

3. **Use the sine addition formula:**

   \[
   \sin(a + b) = \sin(a)\cos(b) + \cos(a)\sin(b)
   \]

4. **Substitute the values:**

   \[
   \sin(a + b) = \left(-\frac{4}{5}\right)\left(-\frac{8}{17}\right) + \left(-\frac{3}{5}\right)\left(\frac{15}{17}\right)
   \]

5. **Calculate:**

   \[
   \sin(a + b) = \frac{32}{85} - \frac{45}{85} = -\frac{13}{85}
   \]

**Answer:**

\(\sin(a + b) = -\frac{13}{85}\)
Transcribed Image Text:**Problem:** If \( \tan(a) = \frac{4}{3} \) and \( \cos(b) = -\frac{8}{17} \), with \( a \) in quadrant III and \( b \) in quadrant II, find \( \sin(a + b) \). Leave your answer in a simplified fraction. **Explanation:** To solve this problem, follow these steps: 1. **Find \(\sin(a)\) and \(\cos(a)\):** Since \(\tan(a) = \frac{4}{3}\), and \(a\) is in quadrant III: \[ \sin(a) = -\frac{4}{5}, \quad \cos(a) = -\frac{3}{5} \] In quadrant III, both sine and cosine are negative. 2. **Find \(\sin(b)\):** Given \(\cos(b) = -\frac{8}{17}\) and \(b\) in quadrant II, where sine is positive and cosine is negative: \[ \sin(b) = \frac{15}{17} \] 3. **Use the sine addition formula:** \[ \sin(a + b) = \sin(a)\cos(b) + \cos(a)\sin(b) \] 4. **Substitute the values:** \[ \sin(a + b) = \left(-\frac{4}{5}\right)\left(-\frac{8}{17}\right) + \left(-\frac{3}{5}\right)\left(\frac{15}{17}\right) \] 5. **Calculate:** \[ \sin(a + b) = \frac{32}{85} - \frac{45}{85} = -\frac{13}{85} \] **Answer:** \(\sin(a + b) = -\frac{13}{85}\)
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