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 Plane Geometry is about flat shapes like lines, circles and triangles ... shapes that can be drawn on a piece of paper
3d shapes Solid Geometry is about three dimensional objects like cubes, prisms, cylinders and spheres.

right arrow Hint: Try drawing some of the shapes and angles as you learn ... it helps.



Point, Line, Plane and Solid

A Point has no dimensions, only position
A Line is one-dimensional
A Plane is two dimensional (2D)
A Solid is three-dimensional (3D)


Why do we do Geometry? To discover patterns, find areas, volumes, lengths and angles, and better understand the world around us.

Plane Geometry

Plane Geometry is all about shapes on a flat surface (like on an endless piece of paper).

2d pentagon




A Polygon is a 2-dimensional shape made of straight lines. Triangles and Rectangles are polygons.

Here are some more:

Pentagon Pentagon
Pentagram Pentagram
Hexagon Hexagon



The Circle

pi circle diameter

Circle Theorems (Advanced Topic)



There are many special symbols used in Geometry. Here is a short reference for you:

Geometric Symbols


Congruent and Similar



Types of Angles

Acute Angles Right Angles Obtuse Angles Straight Angle Reflex Angles Full Rotation



Using Drafting Tools



Transformations and Symmetry


symmetry drawing








More Advanced Topics in Plane Geometry


abc triangle


Conic Sections

ellipse draw 3



triangle showing Opposite, Adjacent and Hypotenuse

Trigonometry is a special subject of its own, so you might like to visit:


Solid Geometry

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:

shapes thumb
Common 3D Shapes

Polyhedra and Non-Polyhedra

There are two main types of solids, "Polyhedra", and "Non-Polyhedra":

Polyhedra :
(they must have flat faces)
hexahedron square prism Cubes and
Cuboids (Volume
of a Cuboid
tetrahedron hexahedron octahedron dodecahedorn icosahedron Platonic Solids
triangular prism square prism pentagonal prism Prisms
triangular pyramid square pyramid pentagonal pyramid Pyramids
(if any surface is not flat)
sphere Sphere torus Torus
cylinder Cylinder cone Cone