For #1-4 , refer to the points P(1 , -1 , 2), Q(2 , 1 , 3) , and R(1, 2, -1). Let u - PQ and let v = PR. 1) A unit vector orthogonal to i and 2) Express u as the product of its speed & direction. Find an equation for the plane through P, Q, and R. 4) Parameterize the line segment joining P and