What is the method used to lay out a fitting with a slant length?

The correct method to lay out a fitting with a slant length is the parallel line development method. This technique is particularly useful when dealing with fittings that are not aligned to the standard geometric projections, such as slanted or sloped ductwork.

In parallel line development, the slant length is accounted for by parallel lines that represent the depth of the fitting. This allows for the accurate creation of patterns for duct fittings, where the angle and the dimensions must be carefully considered to ensure that the configuration fits correctly when assembled. This method simplifies the process of translating the three-dimensional geometry of a fitting into a two-dimensional pattern, allowing for cuts and bends to be made accurately.

The other methods mentioned, such as the radial line method and triangulation, serve different purposes in sheet metal layout and might not be suitable for fittings with slant lengths, as they require more complex geometrical considerations for accurate representation. The straight layout, on the other hand, is typically appropriate for straight pieces of duct without any angles or slopes. Thus, the parallel line development is the most effective method for this specific scenario.