Which term describes a modelling approach where the product is developed using a top-down structure in CAD?

• A. Scale drawings
• B. Sketches
• C. Top-down modelling
• D. Projection drawings

Answer: (C)

In CAD, top-down modelling is about starting with a broad, overall structure and then creating the parts within that framework. This approach lets you establish the big form, functional relationships, and constraints first, so the detailed features are driven by the overall design intent. You build an assembly skeleton or parent geometry, set key dimensions and relationships at the top level, and then add components that automatically fit as changes are made. This makes it easier to keep the whole product consistent when major dimensions change, because dependent parts update accordingly. The other terms describe ways of representing or communicating a design—scale drawings show size at a specific scale, sketches are rough representations, and projection drawings convey orthographic views—none of which capture the idea of developing a product from top to bottom within a CAD system.