Anonymous 1123
I am trying to draw this figure
I tried
```
\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{calc,3dtools}% https://github.com/marmotghost/tikz-3dtools
\begin{document}
\begin{tikzpicture}[3d/install view={phi=70,theta=70,psi=180},scale=1,line cap=butt,line join=round,c/.style={circle,fill,inner sep=1pt},
declare function={Rsphere=3;rcone=2*Rsphere/sqrt(3);h=2*Rsphere;}]
\path
(0,0,0) coordinate (O)
(0,0,h) coordinate (T);
\pic{3d/cone={r=rcone,h=h}};
\draw[3d/screen coords] (O) circle[radius=Rsphere];
\path foreach \p/\g in {O/90,T/-90}
{(\p)node[c]{}+(\g:2.5mm) node{$\p$}};
\draw[3d/hidden] (O) -- (T);
\end{tikzpicture}
\end{document}
```
and get
Top Answer
user 3.14159
One option is to use some clips and reversed clips.
```
\documentclass[tikz,border=3mm]{standalone}
\usetikzlibrary{calc,3dtools}% https://github.com/marmotghost/tikz-3dtools
\begin{document}
\begin{tikzpicture}[3d/install view={phi=0,theta=70,psi=180},scale=1,line cap=butt,line join=round,c/.style={circle,fill,inner sep=1pt},
declare function={Rsphere=3;rcone=2*Rsphere/sqrt(3);h=2*Rsphere;}]
\path
(0,0,0) coordinate (O)
(0,0,h) coordinate (T);
\begin{scope}
\path[3d/cone/inner/.style={3d/hidden},
3d/cone/outer/.style={3d/hidden}]pic{3d/cone={r=rcone,h=h}};
\clip[3d/screen coords,even odd clip] (O) circle[radius=Rsphere]
[generous outside path];
\pic{3d/cone={r=rcone,h=h}};
\end{scope}
\draw[3d/visible] (-rcone,0) arc[start angle=180,end angle=360,radius=rcone];
\begin{scope}
\draw[3d/screen coords,3d/hidden] (O) circle[radius=Rsphere];
\clip[even odd clip]
(-rcone,0) arc[start angle=180,end angle=360,radius=rcone]
-- (rcone,-2*Rsphere) arc[start angle=0,end angle=-180,radius=rcone]
--cycle [generous outside path];
\draw[3d/screen coords,3d/visible] (O) circle[radius=Rsphere];
\end{scope}
\path foreach \p/\g in {O/90,T/-90}
{(\p)node[c]{}+(\g:2.5mm) node{$\p$}};
\draw[3d/hidden] (O) -- (T);
\end{tikzpicture}
\end{document}
```
