I am trying to draw this picture

![ScreenHunter 269.png](/image?hash=a7cf0002e3b2d545274bda569c0eda58b34069fcead7ff0657d15e2ae1d0d0e5)

I tried
```
\documentclass[tikz]{standalone}
\usetikzlibrary{calc,3dtools}% https://github.com/marmotghost/tikz-3dtools
\usetikzlibrary{intersections}
\begin{document}
\begin{tikzpicture}[3d/install view={phi=70,theta=70},line cap=butt,line join=round,c/.style={circle,fill,inner sep=1pt},
		declare function={
			alpha=60; 
			d=6; 
			h=0.5*d*sqrt(3)*sin(alpha); 
			r=sqrt(d*d-h*h); 
			myphi = -60;	myangle=acos((2*r*r-d*d)/(2*r*r)); }]  
		
		\path
		(0,0,0) coordinate (O)
		(0,0,h) coordinate (S)
		({r*cos(myphi)},{r*sin(myphi)},0) coordinate (A)
		({r*cos(myphi+myangle)},{r*sin(myphi+myangle)},0) coordinate (B)
		[3d coordinate = {(M) = 0.5*(A) + 0.5*(B)}]
		;
\path[3d/visible/.style={save named path=cone,draw=none}]  pic{3d/cone={r=r,h=h}};
		\draw[3d/visible] (A) -- (S) -- (B);
		\draw[3d/hidden] (A) -- (O) -- (B) -- cycle
		(S) -- (O) -- (M) -- cycle
		;		
		
		\path pic[red,3d/hidden]{3d incircle={% 
				A={(A)},B={(B)},C={(S)},center name=I}}; 		
		\path[save named path=circle] pic[blue]{3d circle through 3 points={%
				A={(A)},B={(B)},C={(S)},center name=T}};  
		\tikzset{3d/draw ordered paths={cone,circle}}	
		\path foreach \p/\g in {O/130,S/90,A/-90,B/-90,M/-90,T/0,I/180}
		{(\p)node[c]{}+(\g:2.5mm) node{$\p$}};
	\end{tikzpicture}
\end{document}  

```
I got
![ScreenHunter 270.png](/image?hash=5472572b277f2de49888dabfa0421d3af9eb68010d08e04824b3f752ad8c8328)

How to correct  dashed lines of two generators of above cone?