Stage: 3 Challenge Level: 
The $30$ $^\circ$ , $30$ $^\circ$ , $120$ $^\circ$ isosceles triangles are made by bisecting the equilateral triangles and putting the two pieces together the other way - like this:
Rational and irrational numbers. Visualising. Practical Activity. Translations. Generalising. Quadrilaterals. Rotations. Compound transformations. Reflections. Logo.
Published April 2001.
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