Geometry is all about shapes and their properties.
If you like playing with objects, or like drawing, then geometry is for you!
Geometry can be divided into:
Plane Geometry is about flat shapes like lines, circles and triangles ... shapes that can be drawn on a piece of paper
Solid Geometry is about three dimensional objects like cubes, prisms, cylinders and spheres.
|Hint: Try drawing some of the shapes and angles as you learn ... it helps.|
Point, Line, Plane and Solid
Why do we do Geometry? To discover patterns, find areas, volumes, lengths and angles, and better understand the world around us.
Plane Geometry is all about shapes on a flat surface (like on an endless piece of paper).
- Quadrilaterals (Rhombus, Parallelogram, etc)
- Rectangle, Rhombus, Square, Parallelogram, Trapezoid and Kite
- Interactive Quadrilaterals
- Parallelogram In Any Quadrilateral
- Paper Sizes
- Shapes Freeplay
A Polygon is a 2-dimensional shape made of straight lines. Triangles and Rectangles are polygons.
Here are some more:
- Circle Area by Lines
- Circle Sector and Segment
- Circle Area by Sectors
- Activity: Dropping a Coin onto a Grid
Circle Theorems (Advanced Topic)
There are many special symbols used in Geometry. Here is a short reference for you:
Congruent and Similar
Using Drafting Tools
Transformations and Symmetry
More Advanced Topics in Plane Geometry
- Circle Theorems
- Tangent and Secant Lines
- Intersecting Secants Theorem
- Intersecting Chords Theorem
- Angle of Intersecting Secants Theorem
Trigonometry is a special subject of its own, so you might like to visit:
Solid Geometry is the geometry of three-dimensional space - the kind of space we live in ...
... let us start with some of the simplest shapes:
Polyhedra and Non-Polyhedra
There are two main types of solids, "Polyhedra", and "Non-Polyhedra":
Polyhedra (they must have flat faces):
of a Cuboid)
Non-Polyhedra (when any surface
is not flat):
- Polyhedron Models
- Volume and Area of a Sphere Calculator
- Cross Sections
- Triangle Centers
- Vertices, Faces, and Edges
- Cone vs Sphere vs Cylinder
- Pyramid vs Cone
- Prism vs Cylinder
- Volume of Horizontal Cylinder
- Euler's Theorem
- Pythagoras in 3D