\documentclass[a4paper,12pt]{article}
\usepackage{epsfig}
\newcommand{\ds}{\displaystyle}
\newcommand{\pl}{\partial}
\parindent=0pt
\begin{document}


{\bf Question}

A wheel of radius $a$ and centre $C$ rolls along a horizontal
straight line without slipping.  Find the parametric equation for
the locus of a fixed point $P$ on a spoke of the wheel at distance
b from its centre.  Take the x axis as the line through a low
point of the curve and the parameter $t$ as the angle $PCA,$ where
$A$ is the point of contact of the wheel during the rolling.

\vspace{.25in}

{\bf Answer}

${}$

\begin{center}
\epsfig{file=cg-14-1.eps, width=70mm}
\end{center}

${}$

We know: the arc $QL = at$ so $OL = at$ and $PM=b\sin t$ and $CM =
b\cos t$

So the coordinates of P are  \begin{eqnarray*} x & = & at - b\sin
t \\ y & = & a - b\cos t \end{eqnarray*}

\end{document}
