Circle Geometry Concepts and Formulas

This video tutorial explains how to calculate the circumference of a circle using different given values: radius, diameter, and area. It begins with a basic introduction to the concept of circumference and the formula C = 2πr. The tutorial then demonstrates how to find the circumference when the radius is known, followed by a method to calculate it using the diameter. Finally, it covers how to determine the circumference when the area of the circle is provided, using the formula for the area of a circle to find the radius first. Each section includes step-by-step calculations and explanations.

What is the formula to calculate the circumference of a circle using its radius?

• C = πr²

• C = 2πr

• C = πd

• C = 2πd

Tags

CCSS.7.G.B.4

If the radius of a circle is 3 cm, what is the approximate circumference?

• 28.27 cm

• 18.85 cm

• 9.42 cm

• 31.42 cm

Tags

CCSS.7.G.B.4

What unit will the circumference of a circle have if the radius is given in centimeters?

• Centimeters

• Inches

• Square centimeters

• Meters

Tags

CCSS.7.G.B.4

How do you find the radius of a circle if you know the diameter?

• Multiply the diameter by 2

• Divide the diameter by 2

• Square the diameter

• Take the square root of the diameter

Tags

CCSS.7.G.B.4

What is the circumference of a circle with a diameter of 10 inches?

• 20 inches

• 62.8 inches

• 15.7 inches

• 31.4 inches

Tags

CCSS.7.G.B.4

If the diameter of a circle is 10 inches, what is the radius?

• 20 inches

• 10 inches

• 5 inches

• 2 inches

Tags

CCSS.7.G.B.4

What formula is used to find the area of a circle?

• A = 2πr

• A = 2πd

• A = πr²

• A = πd

Tags

CCSS.7.G.B.4

How do you calculate the radius from the area of a circle?

• Multiply the area by 2π

• Divide the area by 2π

• Multiply the area by π and then take the square root

• Divide the area by π and then take the square root

Tags

CCSS.7.G.B.4

What is the approximate circumference of a circle with an area of 113.097 square feet?

• 62.8 feet

• 37.7 feet

• 31.4 feet

• 18.85 feet

Tags

CCSS.7.G.B.4

If the area of a circle is 113.097 square feet, what is the radius?

• 7 feet

• 5 feet

• 6 feet

• 8 feet

Tags

CCSS.7.G.B.4