unitsize(1cm);
import solids;

currentprojection=orthographic(0,100,25);

real r=4, h=7;
triple O=(0,0,0);
triple Oprime=(0,0,3);
triple pS=(0,0,h);
triple pA=(r*sqrt(2)/2,r*sqrt(2)/2,0);
revolution rC=cone(O,r,h,axis=Z,n=1);

draw(surface(rC),blue+opacity(0.5));

skeleton s;
real tOprime=abs(Oprime)/h;
rC.transverse(s,reltime(rC.g,tOprime));
triple pAprime=relpoint(pA--pS,tOprime);
draw(s.transverse.back,dashed);
draw(s.transverse.front);

label("$S$",pS,N);
dot(Label("$O$",align=SE),O);
dot(Label("$O'$",align=SE),Oprime);
dot(Label("$A$",align=Z),pA);
dot(Label("$A'$",align=Z),pAprime);

draw(pS--O^^O--pA^^Oprime--pAprime,dashed);