“…Now, let us suppose that all link dimensions remain unaltered, that is, s 5,9 ′ = s 5,9 , s 6,9 ′ = s 6,9 , s 7,9 ′′ = s 7,9 , and s 8,9 ′′ = s 8,9 , and the orientation of the slider joint is fixed with respect to its adjacent links such that α 1 = π − arctan 5 2 and α 3 = 2π − arctan 5 3 . Then, given the orientations of △P 5 P 6 P 9 ′ and △P 7 P 8 P 9 ′′ , it turns out that α 2 = π − arctan 2 3 and α 4 = 2π − arctan 1 2 .…”