Surface area · Grade 7
In Grade 7 you get fluent with: surface area of rectangular prisms.
Surface area is the total area of all the faces of a solid, measured in square units such as cm². Unfold the solid into its net, find the area of each face, and add them up.
Key facts
- Surface area: add the areas of all the faces (a net helps).
- A cube has 6 equal square faces; a rectangular prism has 3 pairs of matching rectangles.
Worked examples
Example 1
Find the surface area of a cube with edges of 3 cm.
Answer: 54 cm²
Example 2
Find the surface area of a rectangular prism 5 cm by 4 cm by 2 cm.
Answer: 76 cm²
Example 3
A rectangular prism is 6 cm long, 5 cm deep and 4 cm tall. Find its volume and its surface area.
Answer: Volume 120 cm³, surface area 148 cm²
Example 4
A cube has a surface area of 150 cm². How long is each edge?
Answer: 5 cm