A scheme for statically determinate flat lattice-type truss is investigated. The truss has two supports and uniformly loaded at the upper zone. Analytical dependencies of the deflection of the structure and displacement of the movable support from its size, load and number of panels are obtained. It is shown that if the number of panels in multiples of three, the truss cinematically altered, as is clear from the zero determinant of the system of equilibrium equations. The relevant diagram of the possible speeds of the nodes was defined. The system of computer mathematics Maple with induction method was used for output results. This approach was previously proposed and developed by the author in some problems related to the pivotal plane and spatial trusses. It was discovered intermittent character of the dependence of deflection on the number of panels. Asymptotic properties of the solution were found. The features of the solution allow us to optimize the size of the structure.