How to add quotes (BA and CA) like the image?
My code:
\usepackage{tikz}
\usepackage{tkz-euclide}
\usetkzobj{all}
\begin{document}
\begin{tikzpicture}[scale=.28]
%Definindo os vertices
\tkzDefPoint (0,0){B}
\tkzDefPoint (9,0){C}
\tkzDefPoint (14.5,10.66){A}
\tkzDefPoint (4.83,3.55){E}
\tkzDefPoint (10.83,3.55){D}
%Desenhando as retas
\draw (B) -- node[below] {$9$} (C) -- node[right] {$12$} (A) --
node[above left] {$18$} cycle;
\draw (E) -- node[below] {$6$} (D);
%Labels
\node (1) [label=above:{A}] at (A) {};
\node (2) [label=left:{B}] at (B) {};
\node (3) [label=right:{C}] at (C) {};
\node (4) [label=left:{E}] at (E) {};
\node (5) [label=right:{D}] at (D) {};
\end{tikzpicture}
\end{document}
My result:



calclibrary as in e.g. https://tex.stackexchange.com/questions/106207/a-line-parallel-to-an-edge-in-a-tikz-picture/106218#106218 – Torbjørn T. Feb 15 '18 at 23:38