Question

Zone method is used to develop _____________

(a) prism

(b) pyramid

(c) cone

(d) sphere

The question was asked in an internship interview.

My question is based upon Development of Surfaces topic in chapter Development of Surfaces, Isometric Projections, Perspective Projections & Transformation of Projections of Civil Engineering Drawing

Answer 1

Right option is (d) sphere

To elaborate: In this method the sphere is cut into a number of horizontal zones, each of which may be taken as frustum of a cone whose apex is at the extended chords. Now, develop each zone independently by radial line method. For example to develop the zone A, as it is a frustum of a rigid circular cone with its apex o, on the vertical axis of the sphere. Apply radial-line method and obtain the development of the zone.