\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{backgrounds,calc,through}
\begin{document}
\begin{tikzpicture}[scale=3]
\coordinate (A) at (0,0);
\coordinate (AA) at (0,3);
\coordinate (B) at (1.23,0);
\coordinate (BB) at (1.23,2);
 \node (CA) [circle through=(AA)] at (A) {};
 \node (CB) [circle through=(BB)] at (B) {};
\coordinate (C) at (intersection of CA and B--BB);
\coordinate (D) at (intersection of CB and A--AA);
\draw [very thick,color=orange] (A)--node[right] {$3$}(C) (B)--node[right] {$2$}(D) ;
\coordinate (E) at (intersection of C--A and B--D);
\draw [dashed] (E) --node[left] {$1$} ++(0,-1)  ;
\draw[<->,dashed] (A)--node[above] {$?$}(B);
\begin{pgfonlayer}{background}
\fill[color=orange!40] (A) -- ++(0,3) -- ++(-0.2,0) -- ++ (0,-3.2) -- ++ (1.63,0) -- ++ (0,3.2) -- ++ (-0.2,0) -- ++ (0,-3) -- cycle;
\fill[color=blue!20] (A) rectangle (E) (B) rectangle (E);
\end{pgfonlayer}
\end{tikzpicture}
\end{document}