# How to color a curve

How does one color the interior of the elongated circular region in the following figure:

ContourPlot[y^2 - x (x - 1)(x - 3) == 0, {x, -2, 7}, {y, -4, 3}]


Try without "==0"

ContourPlot[y^2 - x (x - 1) (x - 3), {x, -2, 7}, {y, -4, 3}] • But I need only the curve not the surface – Sara yaqob Mar 24 '19 at 20:47

c = ContourPlot[y^2 - x (x - 1) (x - 3) == 0, {x, -2, 7}, {y, -4, 3}] The region you would like colored

R = RegionPlot[y^2 - x (x - 1) (x - 3) < 0 && x < 2, {x, -2, 7}, {y, -4, 3}] Both plotted together

Show[c, R] • Thank you so so much sir. That's what I need. – Sara yaqob Mar 24 '19 at 20:50
• @Sara, You are welcome! – mjw Mar 24 '19 at 20:52
• @Sarayaqob you mistakenly accepted my answer – Xminer Mar 24 '19 at 21:05
• That's okay. Anyway, your answer works. One question is whether or not we can color in the round area only using ContourPlot[]. – mjw Mar 26 '19 at 17:11
• You can color the RegionPlotwith PlotStyle, e.g. R = RegionPlot[ y^2 - x (x - 1) (x - 3) < 0 && x < 2, {x, -2, 7}, {y, -4, 3}, PlotStyle -> Yellow] – rmw Apr 4 '19 at 17:08