Relative size claim: Is an isometric drawing about 50% smaller than an isometric projection of the same object (i.e., does the drawing show lengths at roughly half the projection)?

Introduction / Context:
This item probes a common misconception. The difference between an isometric drawing and an isometric projection is not a “half size” relationship. Understanding the actual scaling prevents dimensioning and visualization errors on technical graphics.

Given Data / Assumptions:

• An isometric drawing typically uses full lengths along axes (no foreshortening factor applied).
• An isometric projection applies a foreshortening factor of about 0.816 of true length.
• The claim says there is a 50% size difference, which is inaccurate.

Concept / Approach:
Numerically, an isometric projection shortens lengths to roughly 81.6% of true. If one compared an isometric drawing (100%) to an isometric projection (~81.6%), the projection is smaller by about 18–20%, not 50%. Therefore, saying the drawing is about 50% smaller than the projection is incorrect and reverses the normal relationship.

Step-by-Step Solution:

Verification / Alternative check:
Draw a 100 mm edge in an isometric drawing and compare to an isometric projection constructed properly; the latter measures near 81.6 mm, confirming the ~18% difference—not 50%.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming a rule-of-thumb “half size”; mixing projection and drawing conventions on the same sheet and then adding true dimensions without clarifying notes.

Final Answer:
Incorrect