Tangent or Velocity:
\[
    \frac{1}{r} 
    \underline{r}'(t)
    =
    \begin{pmatrix}
       1-\lambda \cos{t}
       \\
       \lambda\sin{t}
    \end{pmatrix}
    =
    \begin{pmatrix}
       1\\0
    \end{pmatrix}
    -
    \lambda
    \begin{pmatrix}
       \cos{t}
       \\
       -\sin{t}
    \end{pmatrix}
    =
    \underline{i}
    -
    \lambda\underline{q}(t)
\]
Unit vector:
\[
   \underline{q}(t)
   =
   \begin{pmatrix}
       \cos{t}
       \\
       -\sin{t}
    \end{pmatrix}
    \perp \underline{p}(t)
\]
@Image 2-Fig.svg
<BR>
@Code 2-Fig.tikz.tex height=300px