直圆锥体三维和二维横截面

Question

我想要创建这个：

这是我对 3-D 的 MWE：

\documentclass{article}
\usepackage{siunitx} % SI units
\usepackage{tikz}
\begin{document}
    \begin{tikzpicture}[scale=-1] % <-- inverts the figure
        \def\a{2}  % major
        \def\b{.5} % minor
        \def\h{5}  % height of the cone
        \def\d{3}  % height of the section
        \pgfmathsetmacro{\t}{asin(\b/\h)} % parameter in the paramater form of the base ellipse x=a cos t, y=b sin t
        
        \begin{scope}[cyan,thick]
            \draw (0,0) ellipse ({\a} and {\b});
            \draw (\t:{\a} and {\b}) -- (0,\h) -- (180-\t:{\a} and {\b});
            \begin{scope}[shift={(90:\h-\d)},scale={\d/\h}]
                \fill[blue!20] (\t:{\a} and {\b}) arc(\t:-180-\t:{\a} and {\b}) -- (0,\h) -- cycle;
                \draw (\t:{\a} and {\b}) arc(\t:180-\t:{\a} and {\b});
                \draw[dashed] (180-\t:{\a} and {\b}) arc(180-\t:360+\t:{\a} and {\b})
                (-\a,0) coordinate (L);
            \end{scope}
        \end{scope}
        \begin{scope}[magenta]
            \draw[dashed] (-\a,0)--(-2*\a,0) (0,\h)--(-2*\a,\h) (L)--+(180:1) coordinate (Ld);
            \draw[<->] (-2*\a+.5,0)--+(90:\h) node[midway,right]{\SI{12}{\centi\meter}};
            \draw[<->] (Ld)++(0:.3)--+(90:\d) node[midway,right]{$d$};
        \end{scope}
        %\fill[gray,opacity=0.3,shift={(90:\h-\d)},scale=2.5,xslant=-1,yscale=.3] (-1,1) rectangle (1,-1) node[below,black]{$\alpha$};
    \end{tikzpicture}   
\end{document}

Answer 1

也许是这样，利用fillbetween所提供的库 pgfplots：

\documentclass[border=10pt]{standalone}
\usepackage{siunitx} % SI units
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\usetikzlibrary{fillbetween, backgrounds}
\begin{document}
    \begin{tikzpicture} % <-- inverts the figure
        \def\a{2}  % major
        \def\b{.5} % minor
        \def\h{5}  % height of the cone
        \def\d{3}  % height of the section
        \def\e{.5}  % thickness of the section
        \pgfmathsetmacro{\t}{asin(\b/\h)} % parameter in the paramater form of the base ellipse x=a cos t, y=b sin t

        \tikzset{
            top section/.append style={shift={(90:\h-\d)}, scale={\d/\h}},
            bottom section/.append style={shift={(90:\h-(\d-\e))}, scale={(\d-\e)/\h}}
        }
        
        \begin{scope}[cyan, thick, scale=-1]
            \draw (0,0) ellipse ({\a} and {\b});
            \draw (\t:{\a} and {\b}) -- (0,\h) -- (180-\t:{\a} and {\b});
            
            \draw[top section] (\t:{\a} and {\b}) arc(\t:180-\t:{\a} and {\b});
            \draw[top section, dashed, name path=top arc] (180-\t:{\a} and {\b}) arc(180-\t:360+\t:{\a} and {\b})
            (-\a,0) coordinate (L);
                
            \draw[bottom section, name path=bottom arc] (\t:{\a} and {\b}) arc(\t:180-\t:{\a} and {\b});
            \draw[bottom section, dashed] (180-\t:{\a} and {\b}) arc(180-\t:360+\t:{\a} and {\b})
            (-\a,0) coordinate (M);

            \pgfonlayer{background}
                \fill[red!10, intersection segments={of=top arc and bottom arc, sequence={R* -- L*}}];
            \endpgfonlayer
        \end{scope}
        
        \begin{scope}[blue]
            \draw[->] (-2*\a,-\h) -- +(4*\a,0) node[midway, below] {$0$} node[below] {$x$};
            \draw[dashed] (0,-\h) -- (0,-\b);
            \draw[->] (0,-\b) -- (0,2*\b) node[right] {$y$};
        \end{scope}
        
        \begin{scope}[magenta]
            \coordinate (T) at (2*\a,0);
            \coordinate (B) at (2*\a,-\h);
            
            \draw[dashed] 
                (\a,0) -- (T)
                (L) -- (T |- L) coordinate (S)
                (M) -- (\a,0 |- M) coordinate (N);

            \draw[<->] ([xshift=-10pt]T) -- ([xshift=-10pt]S) node[midway, right] {$10 - y$};
            \draw[<->] ([xshift=-10pt]S) -- ([xshift=-10pt]B) node[midway, right] {$y$};

            \draw[<-] ([xshift=-10pt]\a,0 |- L) -- +(0,0.25);
            \draw[<-] ([xshift=-10pt]N) -- +(0,-0.25);
            \path ([xshift=-10pt]\a,0 |- L) -- ([xshift=-10pt]N) node[midway] {$\Delta_y$};
        \end{scope}
    \end{tikzpicture}   
\end{document}