Cfrgtkky

I am trying to shade in the area of a circle that is cut into three pieces. Here is the code.

documentclass{article}

usepackage{pgfplots}

pgfplotsset{compat=1.15}

usepackage{tkz-euclide}

usetikzlibrary{arrows,shadows,positioning, calc, decorations.markings, 

hobby, quotes,angles,decorations.pathreplacing,intersections}

usepgfplotslibrary{polar}

usepgflibrary{shapes.geometric}

usepgfplotslibrary{fillbetween}

begin{document}



begin{figure}[ht]



centering



begin{tikzpicture}[scale=1.25,line width=1pt]

begin{axis}[

color= white,

xmin=-15, 

xmax=15, 

ymin=-15, 

ymax=15, 

axis equal image, 

axis lines=middle, 

xticklabels={}, 

yticklabels={},

font=scriptsize,

ticks=none,

xlabel = {},

ylabel = {},

inner axis line style={stealth-stealth}

]



draw[black, thick, name path=1] (0,0) circle [radius=12];



addplot[black, domain=-12:12, samples=300, name path = 1] {sqrt(144-x^2)};



addplot[black, domain=-12:12, samples=300, name path = 2] {-sqrt(144-x^2)};



draw[white, name path=3] (-12,0) -- (12,0);



draw[black, dashed] (-3.179,-11.5713) -- (-3.179,11.5713);



draw[black, dashed] (3.179,-11.5713) -- (3.179,11.5713);



%addplot[red, fill opacity=0.20] fill between [of=1 and 2,soft clip= 

{domain=-12:-3.179}];





end{axis}

end{tikzpicture}



caption{Slicing the pie into three pieces of equal area.}



label{pie}



end{figure}



end{document}

Here is the image produced when I leave the last part commented out:

Now, when I uncomment out the last line, this is the result.

While I have the desired shading, the image is now slightly off-center and the axis lines have been drawn, even though I do not want them to. What should I do to fix this?

As for the original question: fillbetween is less "innocent" than one may think, it also sets layers in such a way that the fills are behind the plots. (This is something that I learned from a comment by Stefan Pinnow.) However, the simplest way to get rid of the axes is to say hide axis.

documentclass{article}

usepackage{pgfplots}

pgfplotsset{compat=1.15}

usepgfplotslibrary{fillbetween}

begin{document}



begin{figure}[ht]



centering



begin{tikzpicture}[scale=1.25,line width=1pt]

begin{axis}[hide axis,

xmin=-15, 

xmax=15, 

ymin=-15, 

ymax=15, 

axis equal image, 

font=scriptsize,

]



draw[black, thick, name path=1] (0,0) circle [radius=12];



addplot[black, domain=-12:12, samples=300, name path = 1] {sqrt(144-x^2)};



addplot[black, domain=-12:12, samples=300, name path = 2] {-sqrt(144-x^2)};





draw[black, dashed] (-3.179,-11.5713) -- (-3.179,11.5713);



draw[black, dashed] (3.179,-11.5713) -- (3.179,11.5713);



addplot[red, fill opacity=0.20] fill between [of=1 and 2,soft clip= 

{domain=-12:-3.179}];

end{axis}

end{tikzpicture}

caption{Slicing the pie into three pieces of equal area.}

label{pie}

end{figure}

end{document}

Yet, if you do not want the axes, why don't you just draw the thing with tikz? (In any case, I'd recommend using polar coordinates for that.)

documentclass[tikz,border=3.14mm]{standalone}

begin{document}

begin{tikzpicture}

draw[clip] (0,0) circle (6);

fill[red, fill opacity=0.20] (105:6) rectangle (-6,-6);

draw[dashed] (105:6) -- (-105:6) (75:6) -- (-75:6);

end{tikzpicture}

end{document}

Please note also that one can use the pgfplots library fillbetween, see e.g. here. (I'm not claiming that this answer is particularly original, it is just an example that I had at hand.)

As for your last comment: this is what I suggested

documentclass[tikz,border=3.14mm]{standalone}

begin{document}

begin{tikzpicture}[thick]

pgfmathsetmacro{radius}{4}

draw[clip] (0,0) circle (radius);

fill[red, fill opacity=0.20] (105:radius) rectangle (-radius,-radius);

fill[blue, fill opacity=0.20] ({-radius*sin(15)},radius) rectangle ({radius*sin(15)},-radius);

fill[green, fill opacity=0.20] (75:radius) rectangle (radius,-radius);

draw[dashed] (105:radius) -- (-105:radius) (75:radius) -- (-75:radius);

end{tikzpicture}

end{document}

and this is what I get