Find the length of the arc. Round your answer to the nearest tenth. 270° 12 m

Elementary Geometry For College Students, 7e
7th Edition
ISBN:9781337614085
Author:Alexander, Daniel C.; Koeberlein, Geralyn M.
Publisher:Alexander, Daniel C.; Koeberlein, Geralyn M.
ChapterP: Preliminary Concepts
SectionP.CT: Test
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**Problem Statement:**

Find the length of the arc. Round your answer to the nearest tenth.

**Diagram Explanation:**

The diagram shows a partial circle (arc) with a radius of 12 meters. The central angle that subtends the arc is 270°.

**Solution:**

To find the length of the arc (L), we use the formula for the arc length of a circle, which is:

\[ L = 2 \pi r \left( \frac{\theta}{360} \right) \]

where:

- \( r \) is the radius of the circle.
- \( \theta \) is the central angle in degrees.

In this problem:

- \( r = 12 \) meters
- \( \theta = 270° \)

Substitute the values into the formula:

\[ L = 2 \pi \times 12 \left( \frac{270}{360} \right) \]

First, simplify the fraction:

\[ \frac{270}{360} = \frac{3}{4} \]

Now substitute back into the formula:

\[ L = 2 \pi \times 12 \times \frac{3}{4} = 24 \pi \times \frac{3}{4} = 18 \pi \]

Next, multiply by \( \pi \approx 3.14 \):

\[ L \approx 18 \times 3.14 = 56.52 \]

Round to the nearest tenth:

\[ \boxed{56.5 \text{ meters}} \]

So, the length of the arc is approximately 56.5 meters.
Transcribed Image Text:**Problem Statement:** Find the length of the arc. Round your answer to the nearest tenth. **Diagram Explanation:** The diagram shows a partial circle (arc) with a radius of 12 meters. The central angle that subtends the arc is 270°. **Solution:** To find the length of the arc (L), we use the formula for the arc length of a circle, which is: \[ L = 2 \pi r \left( \frac{\theta}{360} \right) \] where: - \( r \) is the radius of the circle. - \( \theta \) is the central angle in degrees. In this problem: - \( r = 12 \) meters - \( \theta = 270° \) Substitute the values into the formula: \[ L = 2 \pi \times 12 \left( \frac{270}{360} \right) \] First, simplify the fraction: \[ \frac{270}{360} = \frac{3}{4} \] Now substitute back into the formula: \[ L = 2 \pi \times 12 \times \frac{3}{4} = 24 \pi \times \frac{3}{4} = 18 \pi \] Next, multiply by \( \pi \approx 3.14 \): \[ L \approx 18 \times 3.14 = 56.52 \] Round to the nearest tenth: \[ \boxed{56.5 \text{ meters}} \] So, the length of the arc is approximately 56.5 meters.
**Finding the Length of an Arc**

In this example, we are given a circle with a radius of 4 cm and a central angle of 60°. We need to find the length of the arc corresponding to this angle, and then round the answer to the nearest tenth.

### Step-by-Step Explanation

1. **Identify the given information:**
    - Radius (r) = 4 cm
    - Central angle (θ) = 60°

2. **Formula for the Arc Length:**
    The formula to calculate the length of an arc (L) is:
    \[
    L = \frac{\theta}{360°} \times 2\pi r
    \]
    where θ is the central angle in degrees and r is the radius of the circle.

3. **Plug in the values:**
    - θ = 60°
    - r = 4 cm

    Substitute these values into the formula:
    \[
    L = \frac{60}{360} \times 2\pi \times 4
    \]

4. **Simplify the expression:**
    \[
    L = \frac{1}{6} \times 8\pi
    \]

5. **Calculate the arc length:**
    \[
    L = \frac{8\pi}{6}
    \]
    \[
    L = \frac{4\pi}{3}
    \]

6. **Approximate using the value of π (pi ≈ 3.14):**
    \[
    L = \frac{4 \times 3.14}{3}
    \]
    \[
    L \approx \frac{12.56}{3}
    \]
    \[
    L \approx 4.2 \, \text{cm}
    \]

### Conclusion
The length of the arc, rounded to the nearest tenth, is approximately **4.2 cm**.

### Explanation of Diagram
The diagram shows a circle with a radius of 4 cm. A sector of the circle is marked, defined by a central angle of 60°. The arc length of this sector is the part of the circumference that we are calculating.
Transcribed Image Text:**Finding the Length of an Arc** In this example, we are given a circle with a radius of 4 cm and a central angle of 60°. We need to find the length of the arc corresponding to this angle, and then round the answer to the nearest tenth. ### Step-by-Step Explanation 1. **Identify the given information:** - Radius (r) = 4 cm - Central angle (θ) = 60° 2. **Formula for the Arc Length:** The formula to calculate the length of an arc (L) is: \[ L = \frac{\theta}{360°} \times 2\pi r \] where θ is the central angle in degrees and r is the radius of the circle. 3. **Plug in the values:** - θ = 60° - r = 4 cm Substitute these values into the formula: \[ L = \frac{60}{360} \times 2\pi \times 4 \] 4. **Simplify the expression:** \[ L = \frac{1}{6} \times 8\pi \] 5. **Calculate the arc length:** \[ L = \frac{8\pi}{6} \] \[ L = \frac{4\pi}{3} \] 6. **Approximate using the value of π (pi ≈ 3.14):** \[ L = \frac{4 \times 3.14}{3} \] \[ L \approx \frac{12.56}{3} \] \[ L \approx 4.2 \, \text{cm} \] ### Conclusion The length of the arc, rounded to the nearest tenth, is approximately **4.2 cm**. ### Explanation of Diagram The diagram shows a circle with a radius of 4 cm. A sector of the circle is marked, defined by a central angle of 60°. The arc length of this sector is the part of the circumference that we are calculating.
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