A Missing Edge
Part of the Surface Area & Volume section of Coddy's Geometry journey. Lesson 10 of 62.
The formula works backwards too. If you know a box's volume and two of its edges, the formula becomes an equation for the third edge.
This box holds 60 and its base is 5 by 4. Its volume formula says 60 = 5 × 4 × h, so 60 = 20 × h and h = 3. Check it: 5 × 4 × 3 = 60.
On this board the solid sits on the paper. Tap one of its edges, pick the formula, and the board writes the equation in the figure's labels as your own line. Then solve it with the moves, as in Algebra.
Challenge
The box holds 84 and one edge is x + 2. Tap an edge, pick the formula that links the edges to the volume, and solve the equation the board writes for x.
Then press Check.
Try it yourself
Use the figure to find x
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: Pyramids2Volume 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