Introduction / Context:
Engineering documentation must completely define geometry. A 3D object requires three orthogonal dimensions: width (X), height (Y), and depth (Z). The claim that only height and width suffice ignores depth, which determines thickness or extension in the third axis and is essential for fabrication and inspection.
Given Data / Assumptions:
- Orthographic views map 3D geometry onto perpendicular planes.
- At least two views are often required, and frequently three, to show all three dimensions.
- Dimensions—not scale or visual estimation—convey true sizes.
Concept / Approach:
To construct or machine a part, all three dimensions must be known. Omitting depth leaves ambiguity about thickness, hole positions along the third axis, and volume. Even a very thin plate requires a specified thickness tolerance; declaring “zero” depth is still a defined dimension. Therefore, only height and width cannot fully define a 3D object.
Step-by-Step Solution:
Identify the three principal dimensions: width, height, depth.Ensure drawings include views and dimensions that define each axis explicitly.If an object is uniform in one axis (e.g., extrusion), state the length along that axis with appropriate tolerances.Confirm that no features (holes/slots) rely on an undefined third coordinate.
Verification / Alternative check:
Try to program a CNC operation using only height and width; missing depth prevents toolpath definition.
Why Other Options Are Wrong:
Correct: The statement is false; depth is required.Possible if perspective is used: Perspective is a pictorial style, not a substitute for numerical depth.Valid for thin-plate parts only: Even plates need thickness (depth) specified with tolerance.
Common Pitfalls:
Assuming a default thickness; standards discourage undocumented assumptions.Believing scale on paper can replace missing dimensions.
Final Answer:
Incorrect
Discussion & Comments