In descriptive geometry and projection theory, if a planar surface is parallel to a given plane of projection, how will that surface appear in that particular view?

Introduction / Context:
Understanding how surfaces appear relative to projection planes is vital for interpreting multiview drawings. Surface orientation determines whether the view shows true shape, an edge, or a foreshortened shape.

Given Data / Assumptions:

• The surface is parallel to a specific projection plane (e.g., horizontal, frontal, profile).
• Orthographic projection is perpendicular to the plane.
• No perspective distortion is considered.

Concept / Approach:
When a surface is parallel to the plane onto which it is projected, the projection preserves true dimensions and shape. If a surface is perpendicular to the plane, it collapses to a line; if inclined, it appears foreshortened.

Step-by-Step Solution:

Verification / Alternative check:
Place a rectangular plate parallel to a sheet of paper; its outline matches the actual size. Rotate it edge-on and it appears as a line.

Why Other Options Are Wrong:

• As a line or edge: would require the surface to be perpendicular to the plane.
• Foreshortened: occurs for inclined, not parallel, surfaces.
• Oblique surface: describes orientation relative to principal planes, not appearance in a specific view.

Common Pitfalls:
Confusing “parallel” with “inclined”; only perfect parallelism produces true size.

Final Answer:
True size