A spherical sector is a solid generated by revolving a sector of a circle about an axis which passes through the center of the circle but which contains no point inside the sector. If the axis of revolution is one of the radial sides, the sector thus formed is spherical cone; otherwise, it is open spherical sector.
 

Spherical segment is a solid bounded by two parallel planes through a sphere. In terms of spherical zone, spherical segment is a solid bounded by a zone and the planes of a zone's bases.
 

Zone
A zone is that portion of the surface of the sphere included between two parallel planes.
 

Sphere is a solid bounded by closed surface every point of which is equidistant from a fixed point called the center.
 

Frustum of a right circular cone is that portion of right circular cone included between the base and a section parallel to the base not passing through the vertex.
 

Frustum of a regular pyramid is a portion of right regular pyramid included between the base and a section parallel to the base.
 

Frustum of a pyramid (or cone) is a portion of pyramid (or cone) included between the base and the section parallel to the base not passing through the vertex.
 

Cone
The surface generated by a moving straight line (generator) which always passes through a fixed point (vertex) and always intersects a fixed plane curve (directrix) is called conical surface. Cone is a solid bounded by a conical surface whose directrix is a closed curve, and a plane which cuts all the elements. The conical surface is the lateral area of the cone and the plane which cuts all the elements is the base of the cone.
 

Two surfaces or solids are similar if any two corresponding sides or planes are proportional.