**Problem : **
If an arc of the unit circle has length
, what is the measure of the central
angle that intercepts that arc?

**Problem : **
The coordinates of a point on the unit circle are
(0,
sin(*s*)
). What is the value of
*s*
?

**Problem : **
An angle in standard
position intercepts the unit circle at
(*x*, *y*)
. The
arc between (1,0)
and
(*x*, *y*)
has length
*s*
. Solve for
*x*
and
*y*
in terms of
*s*
.

**Problem : **
The $x$-coordinate of a point on the unit circle is
. What are the
possible y-coordinates?

**Problem : **
Is the equation for the unit circle a function?