Orthographic systems: There are three systems commonly used to arrange orthographic views—first-angle, second-angle, and third-angle projection. Assess the accuracy of this statement.

Difficulty: Easy

Correct Answer: Incorrect

Explanation:


Introduction / Context:
Orthographic projection systems define how views are positioned relative to each other on the sheet. Recognizing which systems are standard avoids confusion when interpreting drawings from different regions.


Given Data / Assumptions:

  • Two standard systems are used worldwide: first-angle and third-angle.
  • Standards such as ISO (predominant in many regions) use first-angle; ASME (North America) uses third-angle.
  • “Second-angle projection” is not a standard system for arranging views.


Concept / Approach:
Orthographic systems arise from quadrants formed by object and projection planes. Practical conventions settled on two mirror-image systems for clarity and global standardization. Introducing a “second-angle” arrangement would create ambiguity and is not adopted by standards.


Step-by-Step Solution:
List the accepted systems: first-angle (ISO) and third-angle (ASME).Verify that symbols in the title block indicate which system is used (the truncated cone symbol with view placement).Conclude that the statement claiming three systems (including second-angle) is incorrect.


Verification / Alternative check:
Check any drawing standard reference: only first- and third-angle symbols and view rules are provided; no second-angle arrangement appears.


Why Other Options Are Wrong:
“Correct” contradicts standards. References to ISO-only, auxiliary views, or sheet orientation do not create additional systems; they operate within first- or third-angle frameworks.


Common Pitfalls:
Misreading view placement when switching between European (first-angle) and North American (third-angle) drawings; always consult the projection symbol in the title block.


Final Answer:
Incorrect

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