These are the front and the back views of an ordinary playing die – the sum of the pips on the opposite faces equals 7. Some pips (their centers) are lying in the vertices of an equilateral triangle. An example of such a triangle is shown with the white outline.
How many different equilateral triangles created with the centers of the pips can be spotted on the die?
Eleven equilateral triangles can be spotted on the faces of a die.