Respuesta :

AL2006
 
This is really a long way to go to make something complicated
out of something simple.  The last choice does the job.

cos(180)  =  -1
sin(180)  =   0

So       4 [cos(180) + i sin(180) ]

       =   4 [ -1      +  i (0) ]

       =     -4     yay!