Tikz 画两个椭圆

 

\begin{tikzpicture}[scale=0.8,thick]
\def\a{5}%长半轴
\def\b{3}%短半轴
\def\c{4}%焦半轴
\def\ptsize{2.0pt} %点的半径

%x 轴 和 y轴 
\path[name path=xaxis,thick,draw,->](-6,0)--(6,0) node[right] {$x$};
\path[name path=yaxis,thick,draw,->](0,-6)--(0,6) node[above,right] {$y$};
%x 轴 与 y 轴的交点 
\path [name intersections={of = xaxis and yaxis}];
\coordinate[label=below right:$O$] (O) at (intersection-1);
%画一个椭圆
 \draw [name path = myellipse ] (intersection-1) ellipse (\a cm and \b cm);
 %椭圆与x 轴交点
\path [name intersections={of = xaxis and myellipse}];
\coordinate[label=below right:$A_2$] (a2) at (intersection-1);
\coordinate[label=below left:$A_1$] (a1) at (intersection-2);
%椭圆与y 轴交点
\path [name intersections={of = yaxis and myellipse}];
\coordinate[label=above right:$B_2$] (b2) at (intersection-1);
\coordinate[label=below right:$B_1$] (b1) at (intersection-2);
%焦点
 \coordinate[label=below :$F_1$] (f1) at (-\c,0);
 \coordinate[label=below :$F_2$] (f2) at (\c,0);
 %a b c 的几何意义
 \draw (b2) --(f2) node[midway,above] {$a$};
 \draw (b2) --(O) node[midway,left] {$b$};
 \draw (O) --(f2) node[midway,below] {$c$};
 %阴影部分填充
 \fill [pattern =north west lines,pattern color = black!70](b2)--(O)--(f2)--cycle;
 %画点
 \foreach \p in {O,a1,a2,b1,b2,f1,f2}
		\fill (\p) circle (\ptsize);
 %在图像右侧再画一个焦点在y轴上的椭圆
\begin{scope}[xshift=13cm]
\path[name path=xaxis,thick,draw,->](-6,0)--(6,0) node[right] {$x$};
\path[name path=yaxis,thick,draw,->](0,-6)--(0,6) node[above,right] {$y$};
\path [name intersections={of = xaxis and yaxis}];
\coordinate[label=below right:$O$] (O) at (intersection-1);
%画一个椭圆
 \draw [name path = myellipse ] (intersection-1) ellipse (\b cm and \a cm);
 
\path [name intersections={of = xaxis and myellipse}];
\coordinate[label=below right:$B_2$] (a2) at (intersection-1);
\coordinate[label=below left:$B_1$] (a1) at (intersection-2);

\path [name intersections={of = yaxis and myellipse}];
\coordinate[label=above right:$A_2$] (b2) at (intersection-1);
\coordinate[label=below right:$A_1$] (b1) at (intersection-2);

 \coordinate[label=left :$F_1$] (f1) at (0,-\c);
 \coordinate[label=left :$F_2$] (f2) at (0,\c);
 
 \draw (a2) --(f2) node[midway,above] {$a$};
 \draw (a2) --(O) node[midway,below] {$b$};
 \draw (O) --(f2) node[midway,left] {$c$};
 
 \fill [pattern =north west lines,pattern color = black!70](a2)--(O)--(f2)--cycle;
 
 \foreach \p in {O,a1,a2,b1,b2,f1,f2}
		\fill (\p) circle (\ptsize);

\end{scope}
 
\end{tikzpicture}