Issue with creating equilateral triangle using pgfplots and vertices of triangle

I simply want to create an equilateral triangle in LaTeX using pgfplots. I have computed the vertices of the triangle, and am using addplot coordinates to connect them.

documentclass{article}

usepackage{tikz}
usepackage{pgfplots}

pgfplotsset{compat=1.16}

begin{document}

begin{center}
    begin{tikzpicture}[scale=2]
        begin{axis}[
            axis lines=none,
            xmin=-1,xmax=1,
            ymin=-1,ymax=1,
            xtick=empty, ytick=empty,
            xticklabels=empty, yticklabels=empty,
        ]

            addplot coordinates {(0, -1) (-{sqrt(3)/2}, 0.5) ({sqrt(3)/2}, 0.5) (0, -1)};

        end{axis}
    end{tikzpicture}
end{center}

end{document}

The problem is, the resulting triangle is visually not an equilateral triangle, and instead is isosceles. Is this a scaling issue, or an issue with pgfplots itself? Hopefully my math isn’t wrong!