Worked examples
Two examples
Example 1
What is the surface area of a box 5 in long, 3 in wide and 2 in tall?
- Three pairs of faces: 5 × 3 = 15, 5 × 2 = 10, 3 × 2 = 6.
- 2 × (15 + 10 + 6).
Answer: 62 square inches
Example 2
What is the surface area of a cylinder with radius 2 cm and height 5 cm? Use 3.14.
- Two circles: 2 × 3.14 × 4 = 25.12. The side: 2 × 3.14 × 2 × 5 = 62.8.
- Together.
Answer: 87.92 square cm
Where this is taught: Quiz 35: Volume and Surface Area, “Surface area: unfold it”
The drill
Ten problems
This drill also has challenge problems. They use the same skill, set up the way the GED test sometimes sets up a problem, so that it looks new at first.
How many:
Type each answer, then press Check my answers at the bottom. Commas in large numbers are fine.Write each answer on the line. The answer key, with the reasoning, is on the last page.