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Basic Geometry

Basic Geometry

At a Glance - 3D Objects (Prisms, Cylinders, Cones, Spheres)

Three‐dimensional objects are the solid shapes you see every day, like boxes, balls, coffee cups, and cans.

Here are some helpful vocabulary terms for solids:

  • Face: a flat side of a 3‐dimensional object.
  • Base: one of two parallel, congruent sides of an object.
  • Edge: the intersection of two faces on a solid object. This is a line.
  • Prism: a solid object with two congruent and parallel faces.
  • Pyramid: a solid object with a polygon for a base and triangles for sides.

3D shape

Say Hello to the 3-D Shapes

Rectangular Prism
  • A prism with rectangular bases.
  • There are six faces.
  • All faces meet at 90 degrees.
  • Opposite faces are parallel.
rectangular prism
  • A prism with six congruent faces.
  • All faces meet at 90 degree angles.
  • Opposite faces are parallel.
  • It is a form of rectangular prism.
Triangular Prism
  • A prism with triangular bases.
  • Only the bases are parallel.
triangular prism
Octagonal Prism
  • A prism with octagons for bases.
  • Opposite faces are parallel.
hexagonal prism
Triangular Pyramid, aka Tetrahedron
  • A pyramid with a triangular base.
  • A tetrahedron made up of four equilateral triangles is called a regular tetrahedron.
triangular pyramid
Square Pyramid
  • A pyramid with a square base.
Square pyramid
  • A solid with two parallel circular bases.
  • If you "unwrap" the middle section and lay it flat, it is a rectangle.
  • A solid with a circular base and a curved side that ends in one point
  • It has one vertex.
  • A solid figure where all points are an equal distance from the center point.
  • It's a ball.

Exercise 1

Fill in the blank with always, sometimes, or never. A prism ____________ has parallel bases.

Exercise 2

Fill in the blank with always, sometimes, or never.  A tetrahedron ___________ has 4 equilateral triangles.

Exercise 3

Fill in the blank with always, sometimes, or never.  A prism ___________ has 6 faces.

Exercise 4

Fill in the blank with always, sometimes, or never.  Two faces on a cone are ___________ parallel.

Exercise 5

Fill in the blank with always, sometimes, or never.  In a prism, opposite faces are _________ parallel.