how did it come to 9 for B1? it's for solving The Ambiguous Case SSA for triangle.

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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how did it come to 9 for B1? it's for solving The Ambiguous Case SSA for triangle.

**Triangle Angle Calculation Using the Law of Sines**

**Date and Time:** 11/18/23, 11:52 PM  
**Section:** 6-01-Vida Lumod

The problem discusses calculating unknown angles in a triangle using trigonometric principles.

**Details:**

- **Initial Consideration:** The second possible angle, \( B_2 \approx 171^\circ \), is disregarded because \( A = 40^\circ \) leads to \( A + B_2 > 180^\circ \).

- **Angle Calculations:** Using \( B_1 \approx 9^\circ \), find angle \( C \) by applying the concept that the sum of the angles in a triangle equals \( 180^\circ \).

  \[
  A + B + C = 180^\circ 
  \]

  Therefore:
  
  \[
  C = 180^\circ - A - B_1 \approx 180^\circ - 40^\circ - 9^\circ \approx 131^\circ 
  \]

- **Applying the Law of Sines:** To determine side \( c \):

  \[
  \frac{a}{\sin A} = \frac{c}{\sin C}
  \]

  By substituting the known values:

  \[
  \frac{4}{\sin 40^\circ} = \frac{c}{\sin 131^\circ}
  \]

  Solving for \( c \):

  \[
  c \approx 4.7
  \]

  Results are rounded to the nearest tenth.

- **Conclusion:** There is one triangle with solution \( B \approx 9^\circ \), \( C \approx 131^\circ \), and \( c \approx 4.7 \).

- **Answer Verification:** Previously calculated answers were recorded as: 0.1607 and 41.

This solution uses trigonometric laws to validate the existence and measurements of the triangle formed by given angles.
Transcribed Image Text:**Triangle Angle Calculation Using the Law of Sines** **Date and Time:** 11/18/23, 11:52 PM **Section:** 6-01-Vida Lumod The problem discusses calculating unknown angles in a triangle using trigonometric principles. **Details:** - **Initial Consideration:** The second possible angle, \( B_2 \approx 171^\circ \), is disregarded because \( A = 40^\circ \) leads to \( A + B_2 > 180^\circ \). - **Angle Calculations:** Using \( B_1 \approx 9^\circ \), find angle \( C \) by applying the concept that the sum of the angles in a triangle equals \( 180^\circ \). \[ A + B + C = 180^\circ \] Therefore: \[ C = 180^\circ - A - B_1 \approx 180^\circ - 40^\circ - 9^\circ \approx 131^\circ \] - **Applying the Law of Sines:** To determine side \( c \): \[ \frac{a}{\sin A} = \frac{c}{\sin C} \] By substituting the known values: \[ \frac{4}{\sin 40^\circ} = \frac{c}{\sin 131^\circ} \] Solving for \( c \): \[ c \approx 4.7 \] Results are rounded to the nearest tenth. - **Conclusion:** There is one triangle with solution \( B \approx 9^\circ \), \( C \approx 131^\circ \), and \( c \approx 4.7 \). - **Answer Verification:** Previously calculated answers were recorded as: 0.1607 and 41. This solution uses trigonometric laws to validate the existence and measurements of the triangle formed by given angles.
### Solving an SSA Triangle Using the Law of Sines

The Law of Sines is a fundamental rule in trigonometry that relates the angles and sides of a triangle. Given the measures of angles \( A \), \( B \), and \( C \), and the lengths of the sides \( a \), \( b \), and \( c \) opposite these angles, the Law of Sines states:

\[
\frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C}
\]

#### Determining the Angle \( B \)

**Step 1:** Use the Law of Sines to find angle \( B \).

\[
\frac{a}{\sin A} = \frac{b}{\sin B}
\]

Apply the values given:

\[
\frac{4}{\sin 40^\circ} = \frac{1}{\sin B}
\]

**Solve for \( \sin B \):**

- Cross-multiply to solve for \( \sin B \):

  \[
  \sin B \approx 0.1607
  \]

- Round to four decimal places.

**Step 2:** Identify possible angles for \( B \).

There are two potential angles \( B \) between \( 0^\circ \) and \( 180^\circ \) for which \( \sin B \approx 0.1607 \):

- \( B_1 \approx 9^\circ \) (smaller angle rounded to the nearest degree).
- \( B_2 \approx 171^\circ \) (larger angle rounded).

#### Calculating Angle \( C \)

The possibility of \( B_2 \approx 171^\circ \) is not feasible because:

- Given \( A = 40^\circ \), the sum \( A + B_2 \) would exceed \( 180^\circ \).

Apply angle sum in a triangle:

\[
A + B + C = 180^\circ
\]

- Thus, angle \( C \):

  \[
  C = 180^\circ - A - B_1 \approx 180^\circ - 40^\circ - 9^\circ = 131^\circ
  \]

#### Finding Side \( c \)

Using the Law of Sines again to find \( c \):

\[
\frac{a}{\sin A
Transcribed Image Text:### Solving an SSA Triangle Using the Law of Sines The Law of Sines is a fundamental rule in trigonometry that relates the angles and sides of a triangle. Given the measures of angles \( A \), \( B \), and \( C \), and the lengths of the sides \( a \), \( b \), and \( c \) opposite these angles, the Law of Sines states: \[ \frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C} \] #### Determining the Angle \( B \) **Step 1:** Use the Law of Sines to find angle \( B \). \[ \frac{a}{\sin A} = \frac{b}{\sin B} \] Apply the values given: \[ \frac{4}{\sin 40^\circ} = \frac{1}{\sin B} \] **Solve for \( \sin B \):** - Cross-multiply to solve for \( \sin B \): \[ \sin B \approx 0.1607 \] - Round to four decimal places. **Step 2:** Identify possible angles for \( B \). There are two potential angles \( B \) between \( 0^\circ \) and \( 180^\circ \) for which \( \sin B \approx 0.1607 \): - \( B_1 \approx 9^\circ \) (smaller angle rounded to the nearest degree). - \( B_2 \approx 171^\circ \) (larger angle rounded). #### Calculating Angle \( C \) The possibility of \( B_2 \approx 171^\circ \) is not feasible because: - Given \( A = 40^\circ \), the sum \( A + B_2 \) would exceed \( 180^\circ \). Apply angle sum in a triangle: \[ A + B + C = 180^\circ \] - Thus, angle \( C \): \[ C = 180^\circ - A - B_1 \approx 180^\circ - 40^\circ - 9^\circ = 131^\circ \] #### Finding Side \( c \) Using the Law of Sines again to find \( c \): \[ \frac{a}{\sin A
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