Understanding Circles: Diameters and Circumferences

The video tutorial explains a geometry problem involving two concentric circles, Circle A and Circle B. Circle B's circumference is four times that of Circle A, and the radius of Circle A is given as three. The tutorial guides through calculating the circumference of Circle A, determining Circle B's radius, and then finding the diameters of both circles. Finally, it calculates the difference between the diameters of Circle B and Circle A, which is 18.

What is the relationship between the circumferences of Circle A and Circle B?

• Circle B's circumference is equal to that of Circle A.

• Circle B's circumference is twice that of Circle A.

• Circle B's circumference is three times that of Circle A.

• Circle B's circumference is four times that of Circle A.

If the radius of Circle A is 3, what is its circumference?

• 6π

• 3π

• 12π

• 9π

How do you calculate the circumference of a circle?

• π times the diameter

• π times the radius

• 2π times the radius

• 2 times the diameter

What is the radius of Circle B if its circumference is 24π?

• 6

• 9

• 12

• 15

What is the diameter of Circle B?

• 22

• 20

• 18

• 24

What is the difference between the diameters of Circle B and Circle A?

• 21

• 12

• 15

• 18