a := 1
a.minimum := -2
a.maximum := 2
b := 1
b.minimum := -2
b.maximum := 2
c := 1
c.minimum := -2
c.maximum := 2
d := 1
d.minimum := -2
d.maximum := 2
graph3d.box := true
graph3d.mesh := true
graph3d.view := standard
graph3d.background := black
graph3d.perspective := true
graph3d.resolution := 100
graph3d.highlight := 0
graph3d.shading := 1/2
graph3d.contrast := 1/2
graph3d.transparency := 0
graph3d.color := byheight
graph3d.minimumx := -15
graph3d.maximumx := 15
graph3d.minimumy := -15
graph3d.maximumy := 15
graph3d.minimumz := -15
graph3d.maximumz := 15
graph3d((y^2+(sqrt((x + 4)^2+z^2)- 8)^2=5, z^2+(sqrt((x - 4)^2+y^2)- 8)^2=5))