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
Circumference of parts of circles - Answers
1. The answer
The arc length of the semicircle is \(4 \pi\) units.
(Note that we could also multiply 4 by \(3.14\) to get \(12.56\) units.)
2. The answer
The arc length of the partial circle is \(3.5 \pi\) units.
(Note that we could also multiply \(3.5\) by \(3.14\) to get \(10.99\) units.)
3. The answer
The arc length of the partial circle is \(\frac{1}{2} \pi\) units.
(Note that we could also multiply \(\frac{1}{2}\) by \(3.14\) to get \(1.57\) units.)
4. The answer
The arc length of the semicircle is \(6 \pi\) units.
(Note that we could also multiply 6 by \(3.14\) to get \(18.84\) units.)