Quadrilaterals

 Quadrilateral means “four sides”. Therefore, any four sided shape is a quadrilateral, but the sides have to be straight, and it has to be 2 dimensional.

• Square: Four equal sides. Four equal angles, always 90°.
• Rectangle: Opposite sides are parallel and of equal length. Four equal angles, always 90°.
• Rhombus: Four equal sides. Opposite angles are parallel.
• Trapezium/trapezoid: Has one pairof parallel sides.

How to draw quadrilaterals

If you missed the art class, here will you find how to solve the exercises from your workbook.

Quadrilaterals

• How to draw a square knowing its side

 

• How to draw a square inside a circle.
• How to draw a rectangle.
• How to draw a trapezium/trapezoid.

Triangles

A triangle is a polygon with three sides and three angles. The three angles always add 180º.

There are three special names given to triangles that tell how many sides (or angles) are equal

• Equilateral Triangle: Three equal sides and three equal angles, always 60º.
• Isosceles Triangle: Two equal sides and two equal angles.
• Scalene Triangle: No equal sides and no equal angles.

How to draw triangles.

If you missed the art class, here will you find how to solve the exercises from your workbook.

The triangles

• How to draw an equilateral triangle knowing one side...

• How to draw an equilateral triangle inside a circle
• How to draw an isosceles triangle
• How to draw a scalene triangle 

Basic geometry

Great videos explainig the basics of geometry by 

Shoo Rayner

Colour and photography.

Check the National Geographic webpage. It has beautiful pictures.

LIFE IN COLOUR 

Missing shapes. Optical Illusion.

Missing shapes, phantom shapes or Illusory contours.

These are diferent names for the same optical illusion.  

How many triangles do you see in this picture?

     Phantom shapes are a form of optical illusion where countours are percieved without colour change across the contour. That means that we see a shape that really does not exist.

     These are two simple missing shape optical illusions shown in black and white. The existence of a white triangle can easily be imagined in the top image while your brain can also easily create the existence of a white sphere in the lower image.

Try to find the Star!!!

The Hidden Star Game