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Cardioid Epicycloid Simulation

Circle A rolling without slipping around congruent Circle B

60 FPS Engine
Angle (θ): 0.0°
Point P(x, y): (0, 0)
Revolutions: 0.00
Circle B (Fixed) Circle A (Rolling) Cardioid Path
Speed: 1.0x

Visualization Controls

Circle Radius (r) 75 px

Mathematical Context

A Cardioid is an epicycloid produced by a point $P$ on the circumference of a circle of radius $r$ rolling without slipping around a fixed circle of equal radius $r$.

Parametric Equations
x(θ) = r(2 cos θ - cos 2θ)
y(θ) = r(2 sin θ - sin 2θ)
Polar Form
ρ(θ) = 2r (1 - cos θ)
Notice that as Circle A orbits Circle B by angle $\theta$, Circle A rotates by $2\theta$ around its own moving center to satisfy the non-slip condition.