throughout P, i.e. P is a tangent vector to this circle at and the unit vector  eˆ2   P c) If r and remain constant and increases, will more along the circle P z-axis. through perpendicular to the P is therefore a tangent vector at and the unit vector in this direction is ˆ 3 given by  eˆ3 86
throughout P, i.e. is a tangent vector to this circle at P and the unit vector eˆ2  c) If r and  remain constant and  increases, P will more along the circle through P perpendicular to the z-axis. is therefore a tangent vector at P and the unit vector ˆ 3 in this direction is given by eˆ3  86