When triangulating from the elevation view, which two lines are used to calculate a true length?

The correct choice involves the plan height and elevation length when triangulating from the elevation view to calculate a true length. This method is grounded in the geometric principles used in sheet metal layout, particularly when transitioning from two-dimensional representations to three-dimensional forms.

In this context, triangulation involves creating a right triangle where the lengths of the sides relate to the actual dimensions of the sheet metal piece being fabricated. The plan height corresponds to the vertical dimension from the plan view, while the elevation length refers to the dimension as seen from the side view. By using these two measurements, you are able to derive the true length of a diagonal or angled cut, which is essential for accurate fitting and assembly in sheet metal work.

Understanding the relationship between these dimensions helps fabricators visualize and accurately create the parts needed for construction. This method ensures that the final product matches the design specifications and fits together correctly during assembly.