Radius is the distance from the centre to the edge.
Diameter is the distance from edge to edge (going through the centre).
There are some important of a circle that you need to know how to label:
A chord separates the circle into a major arc and minor arc. Also into the major and minor segment.
We need to know how to calculate arc length using this formula:
Also, know how to calculate the sector area:
The formula to calculate sector area is: °
Below are important formulas you need to be aware of: