Which lines are used to indicate measured distances and end with arrows?

• A. Extension lines
• B. Dimension lines
• C. Center lines
• D. Visible lines

Answer: (B)

Dimension lines are utilized in technical drawings to indicate measured distances between points. They are characterized by their ability to extend from one feature to another, marking the exact length or measurement that is being referenced. At both ends of dimension lines, arrows are displayed to denote the starting and ending points of the measurement, making it clear which features are being measured. This clear visual representation helps anyone interpreting the drawing understand the exact sizes and placements of components.

Extension lines, while related to dimension lines, serve a different purpose; they project from the object being measured to the dimension line itself, helping to visually connect the measurement to the relevant features but do not carry measurements themselves. Center lines are used to indicate the centers of circular features or symmetrical objects, while visible lines represent the actual edges and outlines of the objects in a drawing. Each of these lines plays a specific role in a drawing, but dimension lines are uniquely essential for conveying measurements.