You have 20 equilateral triangles all of the same size as well as the same number of 30°, 30°, 120° isosceles triangles with the shorter sides the same length as the equilateral triangles.

Using these triangles how many differently shaped rectangles can you build? Can you make a square?

The 30°, 30°, 120° isosceles triangles are made by bisecting the equilateral triangles and putting the two pieces together the other way - like this: