Six triangles consist of 12 matches. You can put it this way, draw a circle with the length of the match as the radius, take six segments on the circle with the width of the radius, then connect the six segments with matches, and then connect the endpoints of each segment from the center of the circle, thus forming six triangles. Then two triangles are connected together to form a parallelogram, and then the other of the two triangles forming a parallelogram is combined with the next one.