oh great leehuan is here, i just had a question
when you rotate an area (shells), around a line i.e. y=-1, where the area is bound by an ordinate e.g. (1,0) , x-axis, and y=arcsin(x)
does the gap that is created i.e. from y = 0 -> -1 double? so making a cone-like shape with a gap of cylinder...