Nets and Surface Area
Part of the Surface Area & Volume section of Coddy's Geometry journey. Lesson 32 of 62.
The surface area of a solid is the total area of its outside: how much paper it takes to wrap it with no overlap. Cut a box along some edges and fold it flat, and you get its net, six rectangles in one piece. The surface area is the area of the net.
The faces come in three equal pairs. This box has a top and a bottom of 4 × 3 = 12 each, a front and a back of 4 × 2 = 8 each, and two sides of 3 × 2 = 6 each. Together: 2 × (12 + 8 + 6) = 52.
The rule is Surface area of a cuboid: SA = 2 × (l×w + l×h + w×h). A surface area is an area, so its unit is square: cm², not cm³.
Challenge
Find the surface area of the box: tap the solid, pick the rule that gives its surface area, then press Check.
Try it yourself
Find the marked part of the figure
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Surface Area & Volume
1Solids and Their Parts
Faces, Edges and VerticesPrisms and CylindersPyramids and ConesHeight or Slant Height?Spheres and HemispheresRecap: Parts of Solids4Pyramids
Volume of a PyramidThe Slant HeightHeight From the SlantHeight From the VolumeRecap: Pyramids7Surface Area of Prisms
Nets and Surface AreaVolume or Surface Area?A Missing Edge AgainTriangular PrismsThe Hidden Side FirstRecap: Prism Surfaces2Volume of Prisms
Volume of a CuboidVolume of a PrismAny Triangle EndA Missing EdgeRecap: Prism Volume3Cylinders
Volume of a CylinderHeight From the VolumeRadius From the VolumeEnough to Find It?Recap: Cylinders6Spheres and Hemispheres
Volume of a SphereHalf a SphereRadius From the VolumeSphere in a CylinderRecap: Spheres9Pyramids and Cones Outside
Surface of a PyramidSlant Height FirstSurface of a ConeThe Cone: Slant FirstRecap: Pyramid Surfaces