Circumference and Radius of Circles

This video tutorial by Mr. Backberg explains the concept of the circumference of a circle, which is the distance around its perimeter. It covers two main formulas for calculating circumference: one using the diameter and the other using the radius. The video provides examples of calculating circumference with given radius and diameter values, and also demonstrates how to find the radius when the circumference is known. The tutorial emphasizes the importance of including units in the final answers.

What is the circumference of a circle?

• The radius of the circle

• The area inside the circle

• The distance around the circle

• The diameter of the circle

How is the circumference of a circle related to its perimeter?

• Circumference is double the perimeter

• They are unrelated

• Circumference is half the perimeter

• They are the same

Which formula is used to calculate the circumference when the diameter is known?

• Diameter divided by Pi

• Diameter times Pi

• Radius times Pi

• 2 times Radius times Pi

What is the formula for circumference when the radius is given?

• 2 times Radius times Pi

• Diameter times Pi

• Radius times Pi

• Radius divided by Pi

If a circle has a radius of 9 cm, what is its circumference in terms of Pi?

• 27 Pi

• 18 Pi

• 9 Pi

• 36 Pi

What is the approximate decimal value of the circumference for a circle with a radius of 9 cm?

• 56.52 cm

• 36.00 cm

• 28.27 cm

• 18.84 cm

For a circle with a diameter of 20t, what is the exact circumference in terms of Pi?

• 10 Pi

• 20 Pi

• 30 Pi

• 40 Pi

What is the approximate decimal value of the circumference for a circle with a diameter of 20t?

• 125.66 ft

• 31.42 ft

• 94.25 ft

• 62.83 ft

If the circumference of a circle is 26 M, what is the first step to find the radius?

• Multiply by Pi

• Divide by 2

• Subtract Pi

• Add 2

After dividing the circumference by 2, what is the next step to find the radius?

• Multiply by Pi

• Divide by Pi

• Subtract 2

• Add Pi