\PGset[0.8em]
\begin{picture}   (9, 9)

\drawline     (1,1)(8,1)(8,8)(1,8)(1,1) % R

\put( 4.2  , 4.2){$\scriptstyle R$}

\end{picture}
\quad
% diam = 8
\begin{picture}   (10, 13)

% Ellipse:  u = 5.0  v = 5.0  a = 4.0  b = 4.0  phi = 0.0 Grad
\qbezier(9.0, 5.0)(9.0, 6.6569)(7.8284, 7.8284)
\qbezier(7.8284, 7.8284)(6.6569, 9.0)(5.0, 9.0)
\qbezier(5.0, 9.0)(3.3431, 9.0)(2.1716, 7.8284)
\qbezier(2.1716, 7.8284)(1.0, 6.6569)(1.0, 5.0)
\qbezier(1.0, 5.0)(1.0, 3.3431)(2.1716, 2.1716)
\qbezier(2.1716, 2.1716)(3.3431, 1.0)(5.0, 1.0)
\qbezier(5.0, 1.0)(6.6569, 1.0)(7.8284, 2.1716)
\qbezier(7.8284, 2.1716)(9.0, 3.3431)(9.0, 5.0)

\drawline          (1,5)(9,5) % MN
\drawline          (1,5)(1,12)(6.985,1.527) % MSB
% 1,12 extended through 5,5 by length=4
% slope = 4/7
% 16 = x^2 + (.5714x)^2
% x = 3.473
% y = 1.985
% y/x = 4/7
% y = .5714x
% (ax)^2 = 

\put( 0.1  , 4.7){$\scriptstyle M$}
\put( 3.0  , 9.0){$\scriptstyle C$}
\put( 9.0  , 4.7){$\scriptstyle N$}
\put( 7.2  , 0.7){$\scriptstyle B$}
\put( 0.8  , 12.1){$\scriptstyle S$}

\end{picture}
\quad
\begin{picture}   (17, 9)

% SB = base = 12
% SC = alti =  4
\dashline[80]{0.4}(1,1)(13,1)(16,5)(4,5)(1,1) % R
\dashline[80]{0.2}(8,5)(8,1)

%\dashline{0.2}

\put( 4.9  , 2.9 ){$\scriptstyle R'$}

\end{picture}

\PGrestore