The position vector of a particle moving through space is r(t) = (2 cos t) i + (2 sin t) j + t k (a) Find the velocity and acceleration vectors. Are they orthogonal? (b) If s is the arc length along the path, find ds/dt and the arc length of the portion of the curve for 0 t /2 (c) Find the parametric equations of the tangent line to the path at the point where t = /2