df <- data_frame(t = seq(-pi,0,0.001),
				 x1 = 16 * (sin(t)) ^ 2,
				 x2 = -x1,
				 y = 13* cos(t) - 5 * cos(2*t) -2*cos(3*t) - cos(4*t))

df %>%
	gather(side,x,x1,x2) %>%
	ggplot(aes(x,y)) +
	geom_polygon(fill = "red") +
	coord_fixed() +
	theme_minimal()