Development of a Sphere:
The surface of a sphere is capable to be approximately developed through
(a) Zone method
(b) Lune method.
Following diagram shows the top half of a sphere divided into four zones of equivalent width. By connecting points P, Q, R and S with straight lines, all zone becomes a cone frustum, except the uppermost zone that becomes a cone of small altitude.
Development of these three (3) cone frustums and the upper cone will provide the development of a half sphere. As an example, get the zone C. This is a frustum of cone such vertex is at C1. The surface of this frustum is displayed developed in the front view. The length of the divisions upon the arc is got from the top view. Each the zones can be developed in the similar manner.