Circumference and Area of a Circle
To calculate the circumference (which is like perimeter) and the area of a circle, you need a special irrational number: pi. Pi is the ratio of the circumference of a circle to its diameter. Watch this lecture series to explore the circumference and area of circles, and complete the interactive exercises.
Practice
Radius and diameter - Questions
1. What is the radius and diameter of the following circle?
Radius = _______ cm
Diameter = _______ cm
2. What is the radius and diameter of the following circle?
Radius = _______ cm
Diameter = _______ cm
3. The radius of a circle is 8 units.
What is the diameter of the circle?
________ units
4. The diameter of a circle is 16 units.
What is the radius of the circle?
________ units
5. What is the radius and diameter of the following circle?
Radius = _______ cm
Diameter = _______ cm
6. What is the radius and diameter of the following circle?
Radius = _______ cm
Diameter = _______ cm
7. The radius of a circle is 2 units.
What is the diameter of the circle?
_______ units