circulo.md

library(ggforce)
#> Loading required package: ggplot2

circulo <- data.frame(
  x = 0,
  y = 0,
  r = 1
)

ggplot() +
  geom_circle(aes(x0 = x, y0 = y, r = r), fill = "red", alpha=0.25, data = circulo) +
  coord_fixed() +
  geom_hline(yintercept = 0) +
  geom_vline(xintercept = 0)

^{Created on 2020-10-19 by the reprex package (v0.3.0)}