Do any of the wedge/wing shaped plates have the right angle to make a true hexagon or equilateral triangle?
If not, is there any way to make a regular hexagon using plates?
(I know they can be made with Technic struts and connectors, see this BrickEngineer post for some good examples.)
None of the existing wedges have such angles as they are based on integer numbers for the sides. The closest angle you'll find is probably the 2x4 one:
But even that one is about 3° off (63,43° if I remember enough math), so if you place the 2-length sides of 6 of them on a nice hexagonal shape, there will be noticable gaps at the corners.
In short, if you want to build an hexagon-shaped surface without gap, it probably won't be possible.
However, if you want an hexagonal frame for a particular structure, you can use plates the same way you would use Technic beams and get the same results.
Also, the following modified plates could help, as they feature proper angles:
