Equations for the bottom section of the Web page on parametric equations

\{ \begin{matrix}x & = u_{1}(t) = 1 + \frac{t}{2} , \\ y & = v_{1}(t) = 1; \end{matrix}  \{ \begin{matrix}x & = u_{2}(t) = 1, \\ y & = v_{2}(t) = 1 − \frac{t}{2} ; \end{matrix}

\{ \begin{matrix}x & = u_{3}(t) = 1 + \frac{t}{2} , \\ y & = v_{3}(t) = \frac{1}{2} ; \end{matrix}  \{ \begin{matrix}x & = u_{4}(t) = \frac{3}{2} , \\ y & = v_{4}(t) = 1 − \frac{t}{2} . \end{matrix}

x(t) = \{ \begin{matrix}1 + \frac{4t}{2} & if 0 ≤ t < \frac{1}{4}, \\ \frac{3}{2} & if \frac{1}{4} ≤ t < \frac{1}{2}, \\ 1 + \frac{1−4(t− \frac{1}{2})}{2} & if \frac{1}{2} ≤ t < \frac{3}{4}, \\ 1 & if \frac{3}{4} ≤ t < 1. \end{matrix}

y(t) = \{ \begin{matrix}1 & if 0 ≤ t < \frac{1}{4}, \\ 1 − \frac{4(t− \frac{1}{4})}{2} & if \frac{1}{4} ≤ t < \frac{1}{2}, \\ \frac{1}{2} & if \frac{1}{2} ≤ t < \frac{3}{4}, \\ 1 − \frac{1−4(t− \frac{3}{4})}{2} & if \frac{3}{4} ≤ t < 1. \end{matrix}