How to cut all faces in a specific direction from a point? I'd like to be able to cut the faces belonging to a mesh, from a specific point,  in a specific direction. For example, if I were trying to cut an icosphere from it's center at an angle 30 from the x-axis, like so: 



How would I do this? More importantly, how would I create a script to automate this process? It seems that running 
    bpy.ops.mesh.knife_tool()
only creates an error that reads 

Traceback (most recent call last):
  File "&lt;blender_console&gt;", line 1, in &lt;module&gt;
  File "C:\Program Files\Blender Foundation\Blender\2.76\scripts\modules\bpy\ops.py", line 189, in __call__
ret = op_call(self.idname_py(), None, kw)
RuntimeError: Operator bpy.ops.mesh.knife_tool.poll() failed, context is incorrect


and I can't seem to find any more information about what I would need to do to use it in a script. 

Currently, I only need to make vertical slices, from a specific point to the edge of the mesh.

Thanks for any help.
I'd would use a boolean modifier to go around this. It's a pretty easy way, not quite with the script though but works.
Start  by creating a very thin cube and rotating it by any angle you want, but make sure its cutting through all your mesh. Then give your icosphere a boolean modifier and set this new cube you have created as the mesh to use for boolean operation, don't forget to set the operation to difference.

p.s. It won't work with a plane as a boolean, only cube, just like that: