For a curve C parameterized by the arc length by r(s) let T"(s) = (a(s), b(s)) the unit tangent vector, let N (s) = (c(s), d(s)) be the principal normal. 1. Use the identities N (s) N (s) = T(s) 7(s) = 1 and N(s) 7(s) = 0 and to conclude that (c(s) d(s) = ) +(-b(s), a (s)) y a(s)2 + b(s)2 = 1. . be K > 0 a positive constant. Let's assume that we are in the case (c(s), d(s) ) =