Surface area from a net
The question
cm²
Surface area of a 5 × 5 × 13 box
How it works.
5 × 5 × 13 cm
front and back:2 × 5 × 13 =130
front and back:2 × 5 × 13 =130
the two sides:2 × 5 × 13 =130
front and back:2 × 5 × 13 =130
the two sides:2 × 5 × 13 =130
top and bottom:2 × 5 × 5 =50
front and back:2 × 5 × 13 =130
the two sides:2 × 5 × 13 =130
top and bottom:2 × 5 × 5 =50
total:310
- 01
A net lays all six faces out flat. They come in three matching pairs.
- 02
Front and back are 5 by 13, so that pair is 2 × 5 × 13 = 130.
- 03
The two sides are 5 by 13, so that pair is 2 × 5 × 13 = 130.
- 04
Top and bottom are 5 by 5, so that pair is 2 × 5 × 5 = 50.
- 05
Add the three pairs: 130 + 130 + 50 = 310 square cm.