To make a plane tangent to the cone, just select the outer face of the cone as the first choice in the Plane. I would probably pick another plane as the second reference and make it perpendicular to that plane. (If the base of your cone is on the Front plane, then I would pick the Right or Top plane to be perpendicular to.)
I suppose you could use Wrap to make the teeth, but I would be inclined to make one tooth, then use a circular pattern to generate the rest.
To get the proper length for your tooth, just use pi in your value. If your diameter is 40 mm and you want to have 10 teeth, then the circumfrential pitch of one tooth is 4*pi. Just enter it like that when you define the length.
Looking at the teeth in your picture, they look to be different.
If they are the same, use one of the base planes and do an extruded cut through all projecting out. Then do a circular pattern around.
If they are different, with some being the same, then do a combination of my first suggestion and then create a new plane rotated to the desired angle and do the same extruded cut through all.
Hope this makes sense.
And, this is not a noob question. This can be tricky if you are not familiar with the software.
Big thank you to both Jerry and Scott for getting me onto the right track with this problem!
Just in case it helps someone else, here's the complete process I ended up with:
1) Figured out the angular pitch for the deep tooth and the shallow tooth. There are 2 deep teeth and 4 shallow teeth.
2) Drew contruction lines on the base of the cone and eminating from the center of the cone, with the correct angles for the teeth from step 1. This provided me with intersection points between the base of the cone and the lines.
3) Made a plane tangential to the cone surface and positioned exactly in the midpoint between 2 contruction lines from step 2.
4) Drew a triangle for a single tooth, with 2 vertecies coincidental with construction points from step 2.
5) Did an Extrude Cut.
6) Repeated steps 3 to 5 for the shallow tooth.
7) Used Circular Pattern and Mirror Pattern to position the rest of the cutouts.
Thanks again for all the help!