Remember geometry class when they told you that for any three points there is a unique circle for which all three fall on the circumference? Do you remember how to find the center of that circle? You'll need to if you want to find this cache. It's in a small round black plastic container located at the center of the circle on which the waypoints lie. In other words, it is at the one point on the surface of the earth equidistant from all three waypoints.
Notice the theme. Please do not take anything, and leave only small, round things (unless a travel bug shows up). Please do not post any techniques or other hints when you log your find, even encrypted. Leave it well-covered.
The three waypoints are:
Waypoint 1: N37° 20.678 W122° 07.273
Waypoint 2: N37° 21.845 W122° 05.058
Waypoint 3: N37° 20.353 W122° 03.654
You can check your answers for this puzzle on Geochecker.com.