# Geometry

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

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

## Plane Geometry

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

 2D Shapes Activity: Sorting Shapes Triangles Right Angled Triangles Interactive Triangles Quadrilaterals (Rhombus, Parallelogram, etc) · Rectangle, Rhombus, Square, Parallelogram, Trapezoid, Kite Interactive Quadrilaterals Shapes Freeplay Perimeter Area Area of Plane Shapes Area Calculation Tool Area of Polygon by Drawing Activity: Garden Area General Drawing Tool

### Polygons

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

Here are some more:

 Properties of Regular Polygons Diagonals of Polygons Interactive Polygons

### The Circle

 Circle Pi Circle Sector and Segment Circle Area by Sectors Annulus (Advanced) Circle Theorems Activity: Dropping a Coin onto a Grid

### Symbols

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

### Congruent and Similar

 Congruent Shapes Similar Shapes

### Angles

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

### Using Drafting Tools

Geometric Constructions

### Transformations and Symmetry

Symmetry Artist

Activity: Symmetry of Shapes
Activity: Make a Mandala
Activity: Coloring (The Four Color Theorem)

Tessellations
Tessellation Artist

### Coordinates

Cartesian Coordinates
Interactive Cartesian Coordinates
Hit the Coordinate Game

## More Advanced Topics in Plane Geometry

### Conic Sections

Set of all points
Conic Sections
Ellipse
Parabola
Hyperbola

### Trigonometry

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 ...

Common 3D Shapes

### Polyhedra and Non-Polyhedra

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

Polyhedra :
(they must have flat faces)
 Cubes and Cuboids (Volume of a Cuboid) Platonic Solids Prisms Pyramids

Non-Polyhedra:
(if any surface is not flat)
 Sphere Torus Cylinder Cone

 Vertices, Faces, and Edges Euler's Theorem