Tiling with equilateral triangle

Hoda Bornak

Equilateral Triangle

Move sliders from α to ε in order. Can Equilateral Triangle be used to tile the plane? - If yes, what is the rotation angle? - If no, what is the problem? and, - what other shape is needed to complete the tilings? * This activity is constructed by Nika Nesari and Azadeh, 7th grade students.