What is true about non-isometric lines in a drawing?

Non-isometric lines in a drawing are those lines that do not maintain the same scale as the true dimensions when represented in an isometric projection. In isometric drawing, the three axes are equally spaced, and angles between them are consistent. However, when a line does not align perfectly with these axes, its representation can vary in length.

This variability means that non-isometric lines can indeed appear either longer or shorter than their true lengths, depending on their orientation relative to the isometric axes. For instance, a vertical line might appear shorter if it slants towards one of the isometric planes, or longer if it slants away from them. This perspective is essential for understanding how to accurately interpret or create technical drawings where isometric representations are frequently used.

The other options imply a fixed relationship between the observed and actual length, which does not hold true for non-isometric lines, as their appearance can change based on their angle in relation to the defined isometric axes.