Drawing isocircles on isometric faces: When placing a circular feature on an isometric surface in AutoCAD, should you use the standard Circle tool, or is another command required to create the correct ellipse representation?

Introduction / Context:
In isometric drawings, a true circle on a slanted plane appears as an ellipse when projected. AutoCAD provides a specific way to draw these ellipses so they look correct on the isometric face.

Given Data / Assumptions:

• Isometric faces are represented with isoplanes: ISO Left, ISO Top, ISO Right.
• The Circle command draws true circles in orthographic planes, not ellipses on slanted faces.
• Ellipse command with Isocircle option creates an ellipse oriented to the current isoplane.

Concept / Approach:
Using Circle on an isometric face produces a wrong shape (a circle in the drawing plane rather than an ellipse aligned to the isoplane). The Ellipse–Isocircle option computes the correct major/minor axes based on the isoplane so the feature reads as a circle on that face.

Step-by-Step Solution:
Set the correct isoplane (toggle until the face orientation matches).Run Ellipse and choose the Isocircle option.Specify center and radius/diameter; AutoCAD draws the proper isometric ellipse.Confirm that the standard Circle tool is not appropriate in this context.

Verification / Alternative check:
Compare outputs: Circle vs. Ellipse–Isocircle on an isometric face; only the latter aligns with isometric geometry.

Why Other Options Are Wrong:
“Correct” claims the Circle tool is sufficient, which is not the case; the other conditions (specific isoplane, ORTHO, diameter threshold) do not change the geometric requirement.

Common Pitfalls:
Forgetting to set the right isoplane before placing the isocircle, leading to misaligned ellipses.

Final Answer:
Incorrect