1. How many steel rods are in a truss 50 feet long overall? Explain how to find this number without drawing the truss. 2. By counting the triangles she could see for any length, Jenna says she figured out a pattern for the number of rods. For overall length 7, she sees 7 triangles and 6 rods connecting these triangles, so she writes 7 * 3 + 6 = 27 . For length L, she writes N = 3 L + L - 1 . Explain where she gets the 3 L and the L - 1 in her expression.
