Math Problem Statement

An arc of length 135 ft subtends a central angle 𝜃 in a circle of radius 45 ft. Find the measure of 𝜃 in degrees. (Round your answer to one decimal place.)

Solution

To find the measure of the central angle θ\theta in degrees, we can use the formula that relates the arc length ss, the radius rr, and the angle θ\theta in radians:

θ=sr\theta = \frac{s}{r}

Given:

  • Arc length s=135s = 135 ft
  • Radius r=45r = 45 ft

Substitute the values into the formula:

θ=13545=3 radians\theta = \frac{135}{45} = 3 \text{ radians}

Now, to convert the angle from radians to degrees, use the conversion factor:

1 radian=180π degrees1 \text{ radian} = \frac{180}{\pi} \text{ degrees}

So,

θ (in degrees)=3×180π\theta \text{ (in degrees)} = 3 \times \frac{180}{\pi}

θ3×57.2958171.9 degrees\theta \approx 3 \times 57.2958 \approx 171.9 \text{ degrees}

Thus, the measure of θ\theta is approximately 171.9171.9 degrees.

Would you like further details or have any questions?

Here are five related questions:

  1. How would the angle change if the radius were doubled?
  2. What would the angle be if the arc length was 90 feet instead?
  3. How is the formula for arc length derived?
  4. How do you convert degrees back to radians?
  5. What is the difference between a central angle and an inscribed angle?

Tip: When converting radians to degrees, always remember the conversion factor 180π\frac{180}{\pi}.

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Math Problem Analysis

Mathematical Concepts

Geometry
Circle Geometry

Formulas

Central angle formula: \( \theta = \frac{s}{r} \)
Radian to degree conversion: \( \theta \text{ (in degrees)} = \theta \times \frac{180}{\pi} \)

Theorems

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Suitable Grade Level

Grades 10-12