Cardioide en R.

# Figura 2: Generacion de una cardioide.
# Construccion tomada de: http://mathworld.wolfram.com/Cardioid.html
library(grid)
ori <- c(7.5,8.5)
r <- 2.5
grid.circle(x=ori[1], y=ori[2], r=r, default.units="cm",
gp=gpar(col="red", lwd=2) )
a <- ori+c(0,r)
tet <- seq(pi/2,5*pi/2,length=40)
x <- r*cos(tet)+ori[1]
y <- r*sin(tet)+ori[2]
rad <- sqrt( (x-a[1])^2+(y-a[2])^2 )
grid.circle(x=x, y=y, r=rad, default.units="cm", gp=gpar(col="blue") )