Please help me!

I don't know if this is possible,

Suppose that the waterwheel in Figure 2-12b rotates at 6 revolutions per minute (rpm). You start your stopwatch. Two seconds later, point P on the rim of the wheel is at its greatest height. You are to model the distance d of point P from the surface of the water in terms of the number of seconds t the stopwatch reads.

When does the waterwheel enter and exit the water (over time in seconds)

Use $\displaystyle W(t)=C+AcosB(\theta-D)$

This was the accompanying image, Figure 12.2, the line next to P is an arrow:
http://i38.tinypic.com/mc4t4i.gif