Orthographic Projection — An auxiliary view is an orthographic projection taken on a plane that is not one of the standard principal planes (front, top, or side).

Introduction / Context:
Standard orthographic views show faces parallel to the principal planes without distortion. Inclined faces appear foreshortened in those views. An auxiliary view is introduced to align the projection plane with such a face to reveal its true shape.

Given Data / Assumptions:

• An inclined surface needs true shape and size.
• Projection remains orthographic (projectors parallel).
• The auxiliary plane is oriented parallel to the inclined face.

Concept / Approach:
Orthographic projection on a non-principal plane is still orthographic. By choosing a plane parallel to the feature, foreshortening disappears, allowing accurate dimensioning and inspection.

Step-by-Step Solution:
1) Identify the inclined face causing foreshortening.2) Create an auxiliary plane parallel to that face.3) Project geometry using parallel projectors.4) Dimension features in the auxiliary where they are true size.

Verification / Alternative check:
Lengths measured on the auxiliary view equal model true lengths for edges in the plane, confirming orthographic alignment.

Why Other Options Are Wrong:
Auxiliary views are not perspective or pictorial; they do not require vanishing points.

Common Pitfalls:
Projecting from the wrong base view; mixing pictorial conventions with orthographic standards; missing datum references.

Final Answer:
Correct