Consider the vector function given below. r(t) = (9t, 4 cos(t), 4 sin(t)) (a) Find the unit tangent and unit normal vectors T(t) and N(t). T(t) N(t) = (b) Use this formula to find the curvature. k(t) = Consider the following vector function. r(t) = (2V2t, ezt, e-2t) (a) Find the unit tangent and unit normal vectors T(t) and N(t).