1 + 1

u  :=  {5, -1, 8}

v  := {a, b, c}

u  .  v

Cross[u, v]

Cross[v, u]

Sqrt[3]

Sqrt[4]

Sqrt[r^2]

Norm[u_]  :=  Sqrt[u . u]

Norm[v]

Norm[u]

alpha[t_]  :=  {3 Cos[t],  3 Sin[t],  8 t}

alpha[8]

alpha[Pi]

alpha'[t]

D[alpha[t], t]

alpha''[t]

D[alpha[t], t, t]

Curv[alpha_, t_]  :=  
      Norm[Cross[alpha'[t], alpha''[t]]]/
        Norm[alpha'[t]]^3

\(\(alpha[t]
\)\)

Curv[alpha, t]

Simplify[%]

Curv[alpha_, t_]  :=  
      Simplify[Norm[Cross[alpha'[t], alpha''[t]]]/
          Norm[alpha'[t]]^3]

Curv[alpha, t]