xc = (-1 - sqrt(13))/6
yc = sqrt(1 - xc^2)
zc = 1 - xc
fc = xc*yc*zc

%{
xc = sym((-1 - sqrt(13))/6)
yc = sym(sqrt(1 - xc^2))
zc = sym(1 - xc)
fc = xc*yc*zc
%}

xd = (-1 + sqrt(13))/6
yd = sqrt(1 - xc^2)
zd = 1 - xc
fd = xc*yc*zc

xe = (-1 - sqrt(13))/6
ye = -sqrt(1 - xc^2)
ze = 1 - xc
fe = xc*yc*zc

xf = (-1 - sqrt(13))/6
yf = sqrt(1 - xc^2)
zf = 1 - xc
ff = xc*yc*zc