- (n-2)180: Interior Angle Formula
- A line that intersects a circle at exactly one point.: Tangent
- A line that intersects a circle at exactly two points.: Secant
- An arc whose points are on or between the sides of a central angle.: Minor Arc
- An arc whose points are on or outside of a central angle.: Major Arc
- n(n-3)/2: Diagonal Formula
- piD: Circumference
- pir^2: Area of a Circle