a) Elemental area with uniform cross section
b) Elemental area with non uniform cross section
c) Structural area with uniform cross section
d) Non structural area with non uniform cross section

Answer: a
Explanation: Modeling is one of the basic steps in finite element method. Let us model a stepped shaft consists of discrete no of elements each having a uniform cross sectional area. Average cross section area within each region is evaluated and used to define elemental area with uniform cross sectional area.

A1=A₁’+A₂’/2.