Let
be the measure of the circle rotation.
Let
begin at the
.
When
,
is at maximum point
.
When
,
is at maximum point
.
When
,
is at maximum point
.
Draw the figure :
\.gif\")
Observe the figure :
\



The circle rolls along the
-axis then
and
.


The parametric equations are
and
.
The parametric equations are
and
.