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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:
Making Rectangles, Making Squares
Age 11 to 14
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:
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