Solve both parts and justify the conditions used. Part A: Similar solids have linear scale factor 3 from small to large. Find the surface-area ratio. Part B: In the 45° half-depth oblique convention, an original depth is d. Find its drawn length.

1. Part A reasoning

2. Choose the correct surface or volume formula and keep units and similarity powers consistent.

3. Calculate or simplify this relation.

   $$S_{\text{large}}/S_{\text{small}}=3^2=9$$

4. The volume ratio would instead be 27.

5. Part B reasoning

6. Distinguish the actual spatial object from the stated oblique drawing convention.

7. Calculate or simplify this relation.

   $$d'=18/2=9$$

8. This is a drawing convention, not a change in the solid.

A: The requested value is 9. B: The requested value is 9.

Checks and common pitfalls: The volume ratio would instead be 27. This is a drawing convention, not a change in the solid.