Circle Geometry Concepts and Formulas

Mr. Buffington explains the concept of circumference, the distance around a circle, and how to calculate it using the diameter or radius. He introduces pi, an irrational number approximately 3.14, used in these calculations. The video covers exact and approximate answers for circumference and addresses calculating the perimeter of partial circles, such as semicircles and quarter circles.

What is the circumference of a circle?

• The area inside the circle

• The distance around the circle

• The diameter of the circle

• The radius of the circle

Which of the following best describes Pi?

• A whole number

• An irrational number

• A repeating decimal

• A fraction

What is the approximate value of Pi used in calculations?

• 2.71

• 4.13

• 1.62

• 3.14

What is the formula for calculating the circumference of a circle using the diameter?

• Circumference = 2 x Pi x Radius

• Circumference = Diameter / Pi

• Circumference = Pi x Radius

• Circumference = Pi x Diameter

What is the relationship between circumference and diameter?

• Circumference is Pi times the diameter

• Circumference is double the diameter

• Circumference is the same as the diameter

• Circumference is half the diameter

If a circle has a diameter of 5 cm, what is its exact circumference?

• 10 cm

• 5 Pi cm

• 10 Pi cm

• 5 cm

How do you calculate the approximate circumference of a circle with a diameter of 5 cm?

• 5 - 3.14

• 5 / 3.14

• 5 + 3.14

• 5 x 3.14

What is the approximate circumference of a circle with a diameter of 10 cm?

• 20 cm

• 15.7 cm

• 62.8 cm

• 31.4 cm

If a circle has a diameter of 8 cm, what is its exact circumference?

• 8 Pi cm

• 16 Pi cm

• 24 Pi cm

• 32 Pi cm

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

• Radius is triple the diameter

• Radius is half the diameter

• Radius is double the diameter

• Radius is equal to the diameter