This video tutorial explains how to find the radius of a circle given its circumference. It begins with an introduction to the concepts of circle and circumference, followed by an explanation of the irrational constant pi and its relationship with the diameter. The video then derives the formula for calculating the radius from the circumference and demonstrates its application through examples. Finally, a practice exercise is provided for viewers to apply what they've learned.

What is the term used to describe the distance around a circle?

• Area

• Circumference

• Diameter

• Radius

How is the radius of a circle defined?

• The distance around the circle

• The distance from the center to any point on the circle

• The length of a line segment passing through the center

• The area of the circle

What is the value of pi approximately?

• 2.14

• 5.14

• 3.14

• 4.14

Pi is the ratio of a circle's circumference to its what?

• Volume

• Radius

• Diameter

• Area

What is the relationship between the diameter and the radius of a circle?

• Diameter is half the radius

• Diameter is twice the radius

• Diameter is three times the radius

• Diameter is equal to the radius

What is the formula for the circumference of a circle in terms of diameter?

• C = 2πr

• C = πd

• C = πr²

• C = 2d

What is the significance of pi in the context of circles?

• It is the diameter of the circle

• It is the radius of the circle

• It is the ratio of circumference to diameter

• It is the area of the circle

What is the first step in deriving the radius from the circumference?

• Substitute 2r for the diameter

• Divide both sides by the circumference

• Add pi to both sides

• Multiply both sides by pi

After substituting 2r for the diameter, what is the next step to isolate the radius?

• Raise both sides to the power of negative 1

• Divide both sides by the circumference

• Multiply both sides by 2

• Divide both sides by pi

What is the final formula for the radius in terms of circumference?

• r = C / π

• r = C / 2π

• r = 2C / π

• r = π / C