Math Problem Statement

If AC has a length of 4π in., find AD.

Solution

This problem involves a circle, where ACAC is an arc with a given length of 4π4\pi inches, and the task is to find the length of ADAD. Let's break it down step-by-step.

Step 1: Analyze the Circle and Arc

  • ACAC is an arc of the circle, and its length is given as 4π4\pi inches.
  • AOC\angle AOC is subtended by the arc ACAC at the center of the circle, with the measure of 3030^\circ given.

Step 2: Relationship between Arc Length and Angle

The length of an arc ss in a circle is given by the formula: s=rθs = r \theta where:

  • rr is the radius of the circle,
  • θ\theta is the angle subtended by the arc at the center (in radians).

Here, the arc length s=4πs = 4\pi inches and the angle θ=30\theta = 30^\circ. We need to convert the angle into radians: θ=30×π180=π6radians.\theta = \frac{30^\circ \times \pi}{180^\circ} = \frac{\pi}{6} \, \text{radians}.

Step 3: Solve for the Radius rr

Now, substitute the values into the arc length formula: 4π=r×π6.4\pi = r \times \frac{\pi}{6}. Simplify: r=4ππ/6=24inches.r = \frac{4\pi}{\pi/6} = 24 \, \text{inches}. So, the radius of the circle is r=24r = 24 inches.

Step 4: Find ADAD

The line segment ADAD is half of the diameter of the circle because it passes through the center OO of the circle. Since the radius r=24r = 24 inches, the full diameter ABAB is 2r=482r = 48 inches. Therefore: AD=AB2=482=24inches.AD = \frac{AB}{2} = \frac{48}{2} = 24 \, \text{inches}.

Thus, AD=24AD = 24 inches.

Let me know if you'd like further clarification or have any questions.

Follow-up Questions:

  1. How do you convert degrees to radians?
  2. What is the formula for the length of an arc in a circle?
  3. How is the diameter of a circle related to its radius?
  4. How do you calculate the radius when given the arc length and angle?
  5. What is the central angle in radians for different degrees?

Tip: Always remember to convert angles to radians when using formulas involving arc lengths or angular velocity in a circle.

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Math Problem Analysis

Mathematical Concepts

Geometry
Circle
Arc Length
Trigonometry

Formulas

Arc length formula: s = rθ
Angle conversion: θ = (degrees * π) / 180

Theorems

Central Angle Theorem
Radius-Diameter Relationship

Suitable Grade Level

Grades 10-12