||'''Book'''|| Advanced Engineering Mathematics ||
 ||'''Author'''|| Erwin Kreyszig ||
 ||'''Edition'''|| 8th Edition ||

/* code_begins */

{{{
x=var('x')
a=var('a')
W=det(matrix([[exp((-a/2)*x)*cos(3*x),exp((-a/2)*x)*sin(3*x)],[(-a/2)*exp((-a/2)*x)*cos(3*x)-3*exp((-a/2)*x)*sin(3*x),-a/2*exp((-a/2)*x)*sin(3*x)+3*exp((-a/2)*x)*cos(3*x)]]))        
show(W.full_simplify())}}}

/* code_ends */

 * '''Solution by''': 
   * namdev, teaching,RGIT
   * dilip, teaching,RGIT