7th Grade · Geometry
Surface Area
7.G.B.6
Definition
The total area of all faces (surfaces) of a three-dimensional solid. For a rectangular prism: SA = 2lw + 2lh + 2wh. Measured in square units.
Examples
- A box with faces 15, 20, and 12 cm² (each pair) gives SA = 2(15)+2(20)+2(12) = 94 cm².
- Draw the net to visualize all faces before calculating.
Key rule
Surface area is measured in square units — it's like wrapping paper for the solid.
Memory hook
Add up the area of every face.