抛物面与平面的交点

Question

pspicture 中抛物面与平面的交点？

Answer 1

为了好玩，和 Ti钾Z。

\documentclass[tikz,border=3mm]{standalone}
\usepackage{tikz-3dplot}
\begin{document}
\tdplotsetmaincoords{70}{120}
\begin{tikzpicture}[tdplot_main_coords,
    declare function={para(\x,\y)=4-\x*\x-\y*\y/4;}]
  \draw[dashed] (0,0,0) coordinate (O) -- (2,0,0)
   (0,0,4) -- (O) -- (0,4,0) ({sqrt(3)},2,{para(sqrt(3),2)}) 
   -- (0,2,0) -- (0,2,{para(0,2)});
  \draw[-stealth] (2,0,0) -- (5,0,0) node[left]{$x$};
  \draw[-stealth]  (0,4,0) -- (0,6,0) node[below]{$y$};
  \draw[-stealth]  (0,0,4) -- (0,0,5) node[above]{$z$};
  \draw plot[smooth,domain=0:2,variable=\x] (\x,0,{para(\x,0)});
  \draw plot[smooth,domain=0:{sqrt(3)},variable=\x] (\x,2,{para(\x,2)});
  \draw plot[smooth,domain=0:2,variable=\x] (\x,{2*sqrt(4-\x*\x)},0);
  \draw plot[smooth,domain=0:4,variable=\y] (0,\y,{para(0,\y)});
\end{tikzpicture}
\end{document}