1) What is the shape of surface if a right circular cone is cut by a plane perpendicular to the axis?

2) What is the shape of surface if a right circular cone is cut by a plane making greater angle with axis, more than half of the included angle of the cone?

3) What is the shape of surface if a right circular cone is cut by a plane making the same angle with the axis is parallel to the slant line?

4) What is the shape of surface if a right circular cone is cut by a plane making a smaller angle with the axis, (i.e the plane is not parallel to the slant lined passes through the base)?

5) Which is a practical application of involutes curve?