Circumference and Circle Formulas

The video tutorial explains how to find the circumference of a circle, also known as the perimeter. It introduces two formulas: one using the radius and the other using the diameter. The tutorial provides two examples: the first uses a radius of 4 inches, and the second uses a diameter of 12.44 meters. In each example, the circumference is calculated in both exact form, using the symbol pi, and rounded form, using 3.14 as an approximation for pi. The video emphasizes the importance of including units in the final answer.

What is another term for the perimeter of a circle?

• Area

• Radius

• Diameter

• Circumference

Which formula represents the circumference of a circle using the radius?

• C = πr²

• C = 2πd

• C = πd

• C = 2πr

If the radius of a circle is 4 inches, what is the exact form of its circumference?

• 4π inches

• 16π inches

• 12π inches

• 8π inches

What is the approximate value of π used in the video for calculations?

• 3.16

• 3.15

• 3.14

• 3.13

How do you convert the exact form of circumference to a rounded form?

• Divide by π

• Add 3.14

• Multiply by 2

• Use 3.14 for π

What is the rounded form of the circumference when the radius is 4 inches?

• 26.12 inches

• 24.12 inches

• 25.12 inches

• 23.12 inches

What unit is used for the circumference in the first example?

• Feet

• Meters

• Inches

• Centimeters

What is the first step in calculating the circumference using the radius?

• Add the radius to π

• Multiply the radius by π

• Multiply the radius by 2

• Multiply the radius by 2π

What is the alternative formula for circumference using the diameter?

• C = 2πr

• C = πd

• C = πr²

• C = 2πd

What is the relationship between diameter and radius?

• Diameter is three times the radius

• Diameter is twice the radius

• Diameter is half the radius

• Diameter is equal to the radius