4. Problem 7.1.32 b А. 44.4°, 44.4°, 91.2° В. 20.5°, 20.5°, 139.0° С. 45°, 45°, 90° D. 45.6°, 45.6°, 88.8° Е. 69.5°, 69.5°, 41.0°

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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Question

Find the indicated measure, to the nearest 
tenth.

you are allowed to use a calculator. there is only one answer.  

## Question 4: Problem 7.1.32 b

Choose the correct set of angles for the given problem.

**Options:**

- **A.** 44.4°, 44.4°, 91.2°
- **B.** 20.5°, 20.5°, 139.0°
- **C.** 45°, 45°, 90°
- **D.** 45.6°, 45.6°, 88.8°
- **E.** 69.5°, 69.5°, 41.0°

*Note*: This problem involves selecting the appropriate set of angles, possibly for a geometrical figure or trigonometric problem, based on the given criteria or context.
Transcribed Image Text:## Question 4: Problem 7.1.32 b Choose the correct set of angles for the given problem. **Options:** - **A.** 44.4°, 44.4°, 91.2° - **B.** 20.5°, 20.5°, 139.0° - **C.** 45°, 45°, 90° - **D.** 45.6°, 45.6°, 88.8° - **E.** 69.5°, 69.5°, 41.0° *Note*: This problem involves selecting the appropriate set of angles, possibly for a geometrical figure or trigonometric problem, based on the given criteria or context.
**Question 32:** An isosceles triangle has sides measuring 10 inches, 7 inches, and 7 inches. What are the measures of its angles?

**Solution:**

To find the angles of the isosceles triangle:

1. **Identify the Sides:**  
   The triangle has two equal sides measuring 7 inches each, and a base measuring 10 inches.

2. **Use the Cosine Rule:**  
   To find one of the base angles (let's denote it as \( A \)), we use:
   \[
   \cos(A) = \frac{b^2 + c^2 - a^2}{2bc}
   \]
   where \( a = 10 \), \( b = 7 \), \( c = 7 \).

3. **Calculate:**  
   \[
   \cos(A) = \frac{7^2 + 7^2 - 10^2}{2 \times 7 \times 7} = \frac{49 + 49 - 100}{98} = \frac{-2}{98} = -\frac{1}{49}
   \]
   \[
   A = \cos^{-1}\left(-\frac{1}{49}\right)
   \]

4. **Find Angles:**

   - Two angles are equal since it is an isosceles triangle, so angle \( B = A \).

   - The third angle \( C \) at the base is:
     \[
     C = 180^\circ - 2A
     \]

By calculating with a calculator, you can find the precise measures of the angles as decimals. 

**Conclusion:**  
The base angles \( A \) and \( B \) are approximately equal, and the third angle \( C \) completes the triangle.
Transcribed Image Text:**Question 32:** An isosceles triangle has sides measuring 10 inches, 7 inches, and 7 inches. What are the measures of its angles? **Solution:** To find the angles of the isosceles triangle: 1. **Identify the Sides:** The triangle has two equal sides measuring 7 inches each, and a base measuring 10 inches. 2. **Use the Cosine Rule:** To find one of the base angles (let's denote it as \( A \)), we use: \[ \cos(A) = \frac{b^2 + c^2 - a^2}{2bc} \] where \( a = 10 \), \( b = 7 \), \( c = 7 \). 3. **Calculate:** \[ \cos(A) = \frac{7^2 + 7^2 - 10^2}{2 \times 7 \times 7} = \frac{49 + 49 - 100}{98} = \frac{-2}{98} = -\frac{1}{49} \] \[ A = \cos^{-1}\left(-\frac{1}{49}\right) \] 4. **Find Angles:** - Two angles are equal since it is an isosceles triangle, so angle \( B = A \). - The third angle \( C \) at the base is: \[ C = 180^\circ - 2A \] By calculating with a calculator, you can find the precise measures of the angles as decimals. **Conclusion:** The base angles \( A \) and \( B \) are approximately equal, and the third angle \( C \) completes the triangle.
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