A plane flies 1.2 hours at 150 mph on a bearing of 30° It then turns and flies 2.1. hours at the same speed on a bearing of 120° How far is the plane from its starting point? The plane is miles from its starting point (Round to the nearest whole number)

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 Description:**

A plane flies 1.2 hours at 150 mph on a bearing of 30°. It then turns and flies 2.1 hours at the same speed on a bearing of 120°. How far is the plane from its starting point?

**Graphs and Diagrams Explanation:**

The attached diagram portrays the flight path of the plane. The first segment of the journey is represented by a vector labeled with an angle of 30° from the horizontal. The second segment starts from the endpoint of the first segment and is represented by another vector, which forms an angle of 120° from the direction of the first segment. The diagram aims to illustrate the triangle formed by these two flight segments and the point of origin.

**Calculation:**

Given:
- First leg: 150 mph for 1.2 hours.
- Second leg: 150 mph for 2.1 hours.

1. **Compute the Distances:**
   - Distance of first leg \( a \): \( 150 \, \text{mph} \times 1.2 \, \text{hours} = 180 \, \text{miles} \)
   - Distance of second leg \( b \): \( 150 \, \text{mph} \times 2.1 \, \text{hours} = 315 \, \text{miles} \)

2. **Angle Between the Bearings:**
   - The angle between the two legs of the flight (as shown in the diagram) is \( 120° - 30° = 90° \).

3. **Applying the Cosine Rule to Find the Distance \( c \) from the Starting Point:**
   \[ c = \sqrt{a^2 + b^2 - 2ab \cos(120°)} \]

   *Note:* Because the angle is 120°, \( \cos(120°) = -0.5 \).
   
   \[
   c = \sqrt{180^2 + 315^2 - 2 \cdot 180 \cdot 315 \cdot (-0.5)} 
     = \sqrt{32400 + 99225 + 56700} 
     = \sqrt{188325} 
     \approx 434 \, \text{miles}
   \]

**Answer:**

The plane is approximately **434 miles** from its starting point.
Transcribed Image Text:**Problem Description:** A plane flies 1.2 hours at 150 mph on a bearing of 30°. It then turns and flies 2.1 hours at the same speed on a bearing of 120°. How far is the plane from its starting point? **Graphs and Diagrams Explanation:** The attached diagram portrays the flight path of the plane. The first segment of the journey is represented by a vector labeled with an angle of 30° from the horizontal. The second segment starts from the endpoint of the first segment and is represented by another vector, which forms an angle of 120° from the direction of the first segment. The diagram aims to illustrate the triangle formed by these two flight segments and the point of origin. **Calculation:** Given: - First leg: 150 mph for 1.2 hours. - Second leg: 150 mph for 2.1 hours. 1. **Compute the Distances:** - Distance of first leg \( a \): \( 150 \, \text{mph} \times 1.2 \, \text{hours} = 180 \, \text{miles} \) - Distance of second leg \( b \): \( 150 \, \text{mph} \times 2.1 \, \text{hours} = 315 \, \text{miles} \) 2. **Angle Between the Bearings:** - The angle between the two legs of the flight (as shown in the diagram) is \( 120° - 30° = 90° \). 3. **Applying the Cosine Rule to Find the Distance \( c \) from the Starting Point:** \[ c = \sqrt{a^2 + b^2 - 2ab \cos(120°)} \] *Note:* Because the angle is 120°, \( \cos(120°) = -0.5 \). \[ c = \sqrt{180^2 + 315^2 - 2 \cdot 180 \cdot 315 \cdot (-0.5)} = \sqrt{32400 + 99225 + 56700} = \sqrt{188325} \approx 434 \, \text{miles} \] **Answer:** The plane is approximately **434 miles** from its starting point.
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