Mathematics, Vector Calculus, Learning Mathematics, Math.
dT/ds x N + T x dN/ds But dT/ds = N and N x N = 0 so dB/ds = T x dN/ds dB/ds is orthogonal to B and T, and since there’s only 3 dimensions it must be parallel to N, so dB/ds = τ N , where τ is some constant. What constant exactly? Well dB/ds . N = τ N.N |dB/ds||N|*cos0 = τ |N|^2*cos0 τ = |dB/ds| 🎉