What is the function of hidden lines in a technical drawing?

In technical drawings, hidden lines serve the critical function of indicating features that are not visible from the outside view of an object. These lines are typically represented as dashed or dotted lines, allowing a clear distinction from visible contours and edges. By using hidden lines, drafters provide essential information about the internal aspects or features of an item, such as holes, cutouts, or internal mechanisms, which cannot be seen in the view being depicted. This information is vital for accurately interpreting how the part fits or functions within a larger assembly and ensures that those who work with the drawings have all the necessary details to understand the complete design.

In contrast, other choices do not accurately capture the specific purpose of hidden lines. Visible edges are represented by solid lines, whereas contours are more accurately depicted by lighter or different styles of lines. Dimensions, meanwhile, are typically annotated with specific notation and symbols, not represented by hidden lines. Thus, hidden lines uniquely fulfill the role of depicting unseen features, which is essential for comprehensive and functional technical drawings.