\tikzmath{\fact=2.0;}
\tikzmath{\t=1.05;}
\coordinate (V) at ($\fact*(1,1)$);

\coordinate (R1) at (0,0);
\coordinate (R2) at ($(R1)+(V)$);

\coordinate (S1) at ($\fact*(0.5,-0.5)$);
\coordinate (S2) at ($(S1)+(V)$);


\coordinate (T1) at ($\fact*(-0.0,1)$);
\coordinate (T2) at ($\fact*(1.2,-0.5)$);


\draw [thick,name path=r] (R1) -- (R2);
\draw [thick,name path=s] (S1) -- (S2);
\draw [thick,name path=t] (T1) -- (T2);


\node at ($(R1)!\t!(R2)$) {$r$};
\node at ($(S1)!\t!(S2)$) {$s$};
\node at ($(T1)!\t!(T2)$) {$t$};
