Which term describes non-visible edges and surfaces in a view?

• A. Hidden lines
• B. Center lines
• C. Section lines
• D. Extension lines

Answer: (A)

Hidden lines describe edges and surfaces that aren’t visible in a given view. In drafting, these features are shown with short dashes to indicate what lies behind or inside the object—like a pipe behind a wall or a recessed detail inside a cabinet—so readers understand concealed details without needing a separate sectional view. Other line types serve different purposes: center lines mark symmetry or axes, section lines show where a cross-section is taken, and extension lines are used to extend dimensions beyond the object. Using hidden lines helps you interpret what’s hidden from view when inspecting building plans.