Which kind of tape measure can you use to determine travel when the offset angle is known to be 45 degrees?

The correct answer pertains to the specialized design of the plumber's rule, which is particularly useful in the context of determining travel at a known offset angle of 45 degrees. A plumber's rule features a unique design that incorporates a set of markings to facilitate measurement of vertical and horizontal distances simultaneously.

When measuring at a 45-degree angle, this kind of rule allows for a straightforward reading of the distance because the right triangle formed by the offset and the horizontal and vertical distances is symmetrical. The plumber's rule can be laid out flat against the surfaces being measured, thus providing an accurate representation of the travel distance based on the known angle.

In contrast, other types of rules, like the angle rule, are generally designed for measuring angles and may not have the specific features necessary to accurately measure travel directly. The standard rule and travel rule also may not provide the same ease of measurement at a specific angle, especially in plumbing applications where quick and accurate slope determination is critical.