Plane Geometry

If you like drawing, Geometry is for you!

Plane geometry is all about shapes like lines, circles and triangles ... shapes that can be drawn on a flat surface called a Plane (it is like on an endless piece of paper).

 

dimensions

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)

 

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

Shapes

  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:

Pentagon Pentagon
Pentagram Pentagram
Hexagon Hexagon
   
  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

angles
Types of Angles

Degrees (Angle)
Radians

Congruent Angles
Parallel Lines and Pairs of Angles
Transversal
A Triangle Has 180°

Supplementary Angles
Complementary Angles

Angles Around a Point
Angles on a Straight Line

Interior Angles
Exterior Angles

Interior Angles of Polygons
Exterior Angles of Polygons

 

Compass  

Using Drafting Tools

Geometric Constructions

Using the Protractor
Using the Drafting Triangle and Ruler
Using a Ruler and Compass

 

symmetry drawing

Transformations and Symmetry

Transformations:

Symmetry:

Symmetry Artist

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

 

interactive-cartesian-coordinates  

Coordinates

Cartesian Coordinates
Interactive Cartesian Coordinates
Hit the Coordinate Game
 
 

 

More Advanced Topics in Plane Geometry

abc triangle

Pythagoras

Pythagoras' Theorem
Pythagorean Triples

   

Conic Sections

Set of all points
Conic Sections
Ellipse
Parabola
Hyperbola
   
Right-Angled Triangle

Trigonometry

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

Introduction to Trigonometry
Trigonometry Index