How many line segments are needed to make a row of 6 triangles?

To create a row of 6 triangles, each triangle can be formed using 3 line segments. However, since the triangles share sides, the total number of segments needed will be fewer than 18 (6 triangles × 3 segments each). Specifically, for 6 triangles arranged in a row, you need 10 segments: 3 for the first triangle, 1 additional for each of the 5 shared sides between the triangles, and 3 for the last triangle. Thus, the total number of line segments needed is 15.