Circle Formulas, Circumference & Area
Formula
A special type of equation that shows the relationship between different variables.
Circumference of a Circle is the amount of linear units it takes to go around the circle . Similar to Perimeter
C = πd
C = 2πr
Circumference can be found if you know the radius
Diameter is the line segment that has endpoints on the circumference and goes thru the center point of the circle
D = 2r
In terms of pi
In terms of pi means to leave pi in you answer instead of multiplying by it.
Diameter
The distance across the circle through the center
Circumference
The distance all the way around a circle, like perimeter for polygons.
Radius
The distance from the center of a circle to any point on the circle
Area
The number of square units needed to cover a given surface
Exponent (square)
The number that indicates how many times the base is used as a factor
Pi (ratio)
The ratio of a circle's circumference to its diameter (3.14 or 22/7)
Semi-Circle
half of a circle; 180 degree arc
radius is 1/2 of the diameter, it's endpoins are the center of the circle and a point on the circumference
r = d/2 .