Circumference and Area of a Circle
Completion requirements
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 - Answers
1. Radius \(=9 cm\)
Diameter \(=18 cm\)
2. Radius \(=4.2 cm\)
Diameter \(=8.4 cm\)
3. \(=16\) units
4. \(=8\) units
5. Radius \(=6.5 cm\)
Diameter \(=13 cm\)
6. Radius \(=16 cm\)
Diameter \(=32 cm\)
7. \(=4\) units
