Question

The measurement around the widest part of these holiday bulbs is called their circumference. The formula for circumference is 2π(r) and r is the radius of the circle.

Suppose the radius of a given circle is 1.25 inches. Find the circumference of this circle. Round your answer to the nearest hundredth inches.

Answer 1

To find the circumference of a circle with a radius of 1.25 inches, multiply the radius by 2 to find the diameter, then multiply the diameter by pi (π). The circumference is approximately 7.85 inches when rounded to the nearest hundredth.

Step-by-step explanation:

The student is asking how to find the circumference of a circle with a given radius of 1.25 inches using the formula 2π(r), where π (pi) is approximately 3.14159. To find the circumference, we multiply 2 by π and then by the radius (1.25 inches).

Here's the step-by-step calculation:

1. Multiply the radius by 2 to get the diameter: 1.25 inches × 2 = 2.5 inches.
2. Multiply this diameter by π to find the circumference: 2.5 inches × π ≈ 7.85 inches.
3. Round to the nearest hundredth: The circumference is approximately 7.85 inches.

This method of calculation follows the ancient Greek approach to determine the perimeter of a circle, recognizing π as a crucial constant in the computation.