Math Problem Statement

In a circle with center C and radius 4 meters (m), a central angle of x° intercepts an arc of 5π m as shown in the image. What is the value of x?

Solution

To solve the problem, we need to use the relationship between the arc length, radius, and central angle of a circle. This relationship is given by the formula:

s=rθs = r \theta

where:

  • ss is the arc length,
  • rr is the radius,
  • θ\theta is the central angle in radians.

Step 1: Use the given data

From the problem:

  • s=5πms = 5\pi \, \text{m},
  • r=4mr = 4 \, \text{m},
  • The central angle is xx^\circ, which we must convert to radians for the formula.

In radians, the angle θ\theta (in radians) is related to xx^\circ by:

θ=xπ180\theta = \frac{x \cdot \pi}{180}

Step 2: Substitute into the formula

s=rθs = r \theta

Substitute s=5πs = 5\pi, r=4r = 4, and θ=xπ180\theta = \frac{x \cdot \pi}{180}:

5π=4xπ1805\pi = 4 \cdot \frac{x \cdot \pi}{180}

Step 3: Simplify the equation

Cancel out π\pi from both sides:

5=4x1805 = 4 \cdot \frac{x}{180}

Simplify further:

5=4x1805 = \frac{4x}{180}

Multiply both sides by 180 to eliminate the denominator:

5180=4x5 \cdot 180 = 4x

900=4x900 = 4x

Solve for xx:

x=9004=225x = \frac{900}{4} = 225

Final Answer:

The value of xx is:

x=225x = 225^\circ

Let me know if you need further clarification!


Related Questions:

  1. What is the relationship between degrees and radians, and how does it apply here?
  2. How would the solution change if the radius of the circle was different?
  3. Can you derive the formula for the arc length of a sector?
  4. What happens to the arc length when the central angle doubles?
  5. How does this problem relate to real-world applications of circular motion?

Tip:

Always check whether the angle is in degrees or radians before applying formulas to avoid errors.

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Math Problem Analysis

Mathematical Concepts

Circle Geometry
Radians and Degrees
Arc Length

Formulas

s = rθ (arc length formula)
θ (in radians) = x° × π / 180 (degree to radian conversion)

Theorems

Central Angle Theorem

Suitable Grade Level

Grades 9-12