Let C be the curve: r(t) = (t, t^2, t^3) in R3. Find the equation of the tangent line at P = (2,4,8). In this case should I calculate the unite tanget T= r'(t)/||r'(t)||? Or just the velocity r'(t) = 1i + 2tj + (3t^2)k? How to calculate the tangent equation at the point P?