16. The quadrilateral element shown in the figure has the nodal displacement of {u\, vi, 112, V2, U3, V3, 114, V4} = {-1, 0, -1, 0, 0, 1, 0, 1}.

(a) Find the (s, t) reference coordinates of point A (0.5, 0) using iso-parametric mapping method.

(b) Calculate the displacement at point B whose reference coordinate is (s, t) = (0, —0.5)

(c) Calculate the Jacobian matrix [J] at point B.