Math Problem Statement

The area of a sector of a circle with a central angle of 110° is 65 m². Find the radius of the circle. (Round your answer to one decimal place.)

Solution

The given problem involves finding the radius of a circle based on the area of a sector and the central angle.

The formula for the area AA of a sector of a circle is:

A=θ360×πr2A = \frac{\theta}{360^\circ} \times \pi r^2

Where:

  • AA is the area of the sector,
  • θ\theta is the central angle in degrees,
  • rr is the radius of the circle,
  • π\pi is approximately 3.1416.

From the problem, we know:

  • The area of the sector A=65m2A = 65 \, \text{m}^2,
  • The central angle θ=110\theta = 110^\circ.

Step 1: Plug the known values into the formula.

65=110360×πr265 = \frac{110}{360} \times \pi r^2

Step 2: Simplify the fraction.

110360=1136\frac{110}{360} = \frac{11}{36}

Thus, the equation becomes:

65=1136×πr265 = \frac{11}{36} \times \pi r^2

Step 3: Solve for r2r^2.

First, multiply both sides by 3611\frac{36}{11}:

65×3611=πr265 \times \frac{36}{11} = \pi r^2

212.73=πr2212.73 = \pi r^2

Now, divide both sides by π\pi:

r2=212.73π=212.733.1416=67.69r^2 = \frac{212.73}{\pi} = \frac{212.73}{3.1416} = 67.69

Step 4: Take the square root to find rr.

r=67.698.2mr = \sqrt{67.69} \approx 8.2 \, \text{m}

Thus, the radius of the circle is approximately 8.2m8.2 \, \text{m}.

Would you like further clarification or more details?

Here are 5 related questions you might explore:

  1. How do we derive the formula for the area of a sector of a circle?
  2. What happens to the area of a sector if the central angle is doubled but the radius remains the same?
  3. Can you calculate the circumference of the full circle using this radius?
  4. How would the formula change if the central angle was given in radians instead of degrees?
  5. How can you apply this formula to calculate the area of a segment instead of a sector?

Tip: Always ensure the angle is in degrees (or convert to radians if needed) before applying sector-related formulas!

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Math Problem Analysis

Mathematical Concepts

Geometry
Circular Sectors
Algebra

Formulas

Area of sector: A = (θ / 360) * π * r²

Theorems

Basic Circle Theorems

Suitable Grade Level

Grades 9-12