Math
Surface area.
Definition
The total area of all the faces or surfaces of a three-dimensional figure. Surface area is measured in square units and tells you how much material would be needed to cover the outside of a solid.
Examples
Real-world.
- 1 A rectangular box 3×4×5 has surface area 2(3·4 + 3·5 + 4·5) = 94 square units
- 2 A cylinder with radius 3 and height 7 has surface area 2π(3)² + 2π(3)(7) = 60π
- 3 Calculating how much wrapping paper is needed for a gift box
Key Fact
Rectangular prism: SA = 2(lw + lh + wh); Cylinder: SA = 2πr² + 2πrh