20. 5) (3 pts) Surfaces and edges that cannot be seen from the outside of the object are identified by: 25. a) Hidden Lines b) Invisible lines c) Dotted Lines d) Phantom Lines 26) (3 pts) The a) Diameter symbol indicates what term? b) Hole Center c) Zero d) Radius 27) (3 pts) Specify the type of surface A labeled on the part below: a) Inclined b) Principal c) Oblique 28) (3 pts) specify the type of surface B labeled on the part below: a) Inclined b) Principal c) Oblique B