x(t) = a cos(t) y(t) = a sin(t)

x^2 + y^2 = a^2

r(θ) = a

(for a circle with center at the origin and radius a)

algebraic | closed | conic | constant-width | convex | parametric | polar | quadratic | simple

r = a

d = 2 a

C = 2 π a

A = π a^2

s = 2 π a

d = 2

e = 0

evolute | point at origin involute | circle involute

mean line segment length | s^_ = (4 a)/π (where lengths and areas refer to line segments and triangles picked at random from points on the curve)