We have found the exact analytical expressions for the optimal geometry and minimum mass of a diagonal truss beam made of a material with properties of linear creep. We have derived simple analytical expressions for the deflection of the optimal weight of the truss. The deflection of the truss was calculated by the Maxwell - Mohr formula. We found solution generalizations for any number of panels by induction. The research was carried out with the support of the Maple computer mathematics system in symbolic form. The multifunctional Lira software package intended for the design and numerical calculation of buildings and engineering structures was used for comparing and testing the solutions.