Re: On Q9
One word in addition  with triangles we can't afford the convenience of having arbitrarily many vertices (as with convex sets in general  just stating the obvious). It might therefore be useful to keep in mind that the triangle's vertices don't have to rest on the circle, though the data points better do. As the question states, for a point to be covered (h(x)=+1) it suffices if it lies within the triangle, not necessarily directly on its edges or vertices.
