The distance around the outside of a circle, calculated as C = 2πr or C = πd.
Circumference is the perimeter of a circle. It's the total length of the boundary if you "unrolled" the circle into a straight line.
Area = πr², so if you know circumference: r = C/(2π), then Area = C²/(4π).
A bicycle wheel with 26-inch diameter: C = π × 26 ≈ 81.7 inches. Each revolution covers about 6.8 feet.
A number expressed as a fraction of 100, used to describe proportions and rates of change.
A measure of the spread or dispersion of a data set from its mean (average).
Three measures of central tendency used to describe the center of a data set.
A fundamental relation in geometry: the square of the hypotenuse equals the sum of squares of the other two sides.
Area measures the surface inside a shape (in square units); perimeter measures the distance around it.
A number representing a part of a whole, written as a numerator over a denominator.