Find sin 2π ( (27) :)) COS 3 Show your work.

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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cannot use a calculator like a TI-89 or a TI-nSprire CA way, please

### Problem Statement

Find \( \sin^{-1} \left( \cos \left( \frac{2\pi}{3} \right) \right) \). Show your work.

### Solution

To find \( \sin^{-1} \left( \cos \left( \frac{2\pi}{3} \right) \right) \), follow these steps:

1. **Evaluate \(\cos \left( \frac{2\pi}{3} \right)\):**

2. **Analyze the unit circle** to determine the cosine value at \( \frac{2\pi}{3} \).
   - \( \frac{2\pi}{3} \) is located in the second quadrant of the unit circle.
   - The reference angle for \( \frac{2\pi}{3} \) is \( \pi - \frac{2\pi}{3} = \frac{\pi}{3} \).

3. **Determine the cosine value** for this angle:
   - In the second quadrant, cosine is negative.
   - \( \cos \left( \frac{2\pi}{3} \right) = -\cos \left( \frac{\pi}{3} \right) \).
   - Since \( \cos \left( \frac{\pi}{3} \right) = \frac{1}{2} \),
     \[
     \cos \left( \frac{2\pi}{3} \right) = -\frac{1}{2}.
     \]

4. **Solve \( \sin^{-1} \left( -\frac{1}{2} \right) \):**
   - The inverse sine problem \( \sin^{-1} \left( x \right) \) means finding an angle whose sine is \( x \).
   - For \( x = -\frac{1}{2} \),
   - The angle \(-\frac{\pi}{6}\) (or in some conventions, \(\frac{11\pi}{6}\)) has a sine of \(-\frac{1}{2}\).

Therefore,
\[
\sin^{-1} \left( \cos \left( \frac{2\pi}{3} \right) \right) = \sin^{-1} \left( -\frac{1}{2} \right) = -\frac{\pi}{
Transcribed Image Text:### Problem Statement Find \( \sin^{-1} \left( \cos \left( \frac{2\pi}{3} \right) \right) \). Show your work. ### Solution To find \( \sin^{-1} \left( \cos \left( \frac{2\pi}{3} \right) \right) \), follow these steps: 1. **Evaluate \(\cos \left( \frac{2\pi}{3} \right)\):** 2. **Analyze the unit circle** to determine the cosine value at \( \frac{2\pi}{3} \). - \( \frac{2\pi}{3} \) is located in the second quadrant of the unit circle. - The reference angle for \( \frac{2\pi}{3} \) is \( \pi - \frac{2\pi}{3} = \frac{\pi}{3} \). 3. **Determine the cosine value** for this angle: - In the second quadrant, cosine is negative. - \( \cos \left( \frac{2\pi}{3} \right) = -\cos \left( \frac{\pi}{3} \right) \). - Since \( \cos \left( \frac{\pi}{3} \right) = \frac{1}{2} \), \[ \cos \left( \frac{2\pi}{3} \right) = -\frac{1}{2}. \] 4. **Solve \( \sin^{-1} \left( -\frac{1}{2} \right) \):** - The inverse sine problem \( \sin^{-1} \left( x \right) \) means finding an angle whose sine is \( x \). - For \( x = -\frac{1}{2} \), - The angle \(-\frac{\pi}{6}\) (or in some conventions, \(\frac{11\pi}{6}\)) has a sine of \(-\frac{1}{2}\). Therefore, \[ \sin^{-1} \left( \cos \left( \frac{2\pi}{3} \right) \right) = \sin^{-1} \left( -\frac{1}{2} \right) = -\frac{\pi}{
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