Problem 4.1: If an arc of the unit circle has length

, what is the measure of the central angle that intercepts that arc? [Solution]

Problem 4.2: The coordinates of a point on the unit circle are (0, sin(s)). What is the value of s? [Solution]

Problem 4.3: 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. [Solution]

Problem 4.4: The $x$-coordinate of a point on the unit circle is

. What are the possible y-coordinates? [Solution]

Problem 4.5: Is the equation for the unit circle a function? [Solution]