(10 pts) Find the work done by the force field
F(x,y,z)=-(1)/(2)i-(1)/(2)j+(1)/(4)k
in moving a particle along the helix curve
C
given by
r(t)=costi+sintj+tk
from
(1,0,0)
to
(-1,0,3\pi )
show in the figure.