Spheres and Hemispheres
Part of the Surface Area & Volume section of Coddy's Geometry journey. Lesson 5 of 62.
A sphere is a ball: every point on its surface is the same distance from its centre. That distance is the radius, and it is the only measure a sphere has. Twice the radius is the diameter, the width of the ball through its centre.
Cut a sphere through its centre and you get two hemispheres, like a bowl. A hemisphere has a curved surface and a flat circle where it was cut. That circle has the same radius as the sphere.
A sphere has no faces, no edges and no vertices: its whole surface is curved. That is why its formulas, later in this section, use only the radius.
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
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