In two dimensional problems x-, y- co-ordinates are mapped onto ____
a) x-, y- co-ordinates
b) x-, ξ – co-ordinates
c) η-, y- co-ordinates
d) ξ-η-Co-ordinates

Answer: d
Explanation: The similarity with one dimensional element should be noted ; in one dimensional problem the x- co-ordinates were mapped onto ξ- co-ordinates and the shape functions were defined as functions of ξ. In the two dimensional elements the x-, y-, co-ordinates are mapped onto ξ-,,η – co-ordinates.