I want to draw the two arcs you see in the second picture (Autocad drawing). These two arcs are a portion of these two ellipses, respectively:
Ellipse 1:
- x radius=10.15
- y radius=2.15
- center=(0,0)
Ellipse 2:
- x radius=14.4221
- y radius=3.0521
- center=(0,0)
\documentclass[12pt,twoside,openright]{report}
\usepackage{amsfonts,amssymb,amsmath,float,bm,tikz,subcaption,graphicx,textcomp,gensymb,pgfplots} \usetikzlibrary{patterns}
\begin{document}
\begin{figure} [H]
\centering
\begin{tikzpicture}[thick, scale=0.5]
\shadedraw[top color=gray, bottom color=gray!30!white, draw=black] (-5.6082,-4.3226) -- (-5.6082,0) arc(-180:0:5.6082 and 1.1869) -- (5.6082,-4.3226) arc(0:-180:5.6082 and 1.1869);
\draw[dashed] (-5.6082,0) arc(180:0:5.6082 and 1.1869);
\draw (-5.6082,0) -- (-5.6082,4.3226);
\draw (5.6082,0) -- (5.6082,4.3226);
\draw[teal,arrows=->] (0,0) -- (-10.9211,6.6104) node[pos=1,above=2pt]{$x$};
\draw[teal,arrows=->] (0,0) -- (-13.0336,-3.2048) node[pos=1,below=2pt]{$y$};
\draw[teal,arrows=->] (0,0) -- (0,8) node[pos=1,right=2pt]{$z$};
\draw[violet,arrows=->] (0,0) -- (-11.8797,3.0548) node[pos=1,above=2pt]{$r$};
\draw[violet,arrows=->] (-3.5638,0.9164) -- (-12.8766,-0.9233) node[pos=1,above=2pt]{$\theta$};
\draw[violet,arrows=->] (0,0) -- (11.8797,-3.0548) node[pos=1,above=2pt]{$r$};
\draw[violet,arrows=->] (3.5638,-0.9164) -- (12.8766,0.9233) node[pos=1,above=2pt]{$\theta$};
\node[circle,fill,inner sep=2pt,label=below:{$\textbf{A}$}] at (-3.5638,0.9164){};
\node[circle,fill,inner sep=2pt,label=above:{$\textbf{B}$}] at (3.5638,-0.9164){};
\draw (-3.3527,2.0293) arc (149:166:10.15 and 2.15);
\draw (-4.7599,2.8811) arc (149:346:14.4221 and 3.0521);
\end{tikzpicture}
% \caption{Sistema brazo-flotador}
% \label{fig:sistema_brazo_flotador}
\end{figure}
\end{document}
Arc obtained:
Expected arc:
Best Answer
As the figure is auto generated, it is really hard to make sense of the coordinates and angles. -so I just guessed the angles involved. For a better result, it would be easier to start over and use polar coordinates when needed.