Let y(t) be a regular plane curve and let be a constant. The parallel curve of y is defined by y(t) = y(t) + An, (t). 10. Let y(t) be a regular plane curve and let be a constant. The parallel curve of y is defined by (t) = y(t) + Ans(t). 2 Show that if Ak, (t)| < 1 for all values of t, then is a regular curve and that its signed curvature is K/1 - Aks.