( cos ⁡ θ + i sin ⁡ θ ) n = cos ⁡ n θ + i sin ⁡ n θ displaystyle (cos theta +isin theta )^ n =cos ntheta +isin ntheta Each and every family members of parallel strains in a very offered course is postulated to converge for the corresponding suitable stage. This really is carefully connected to the idea of vanishing factors in viewpoint