Determine which families of grid curves have u constant and which have v constant. u constant each grid curve is a helix each grid curve is a vertically oriented circle each grid curve lies in a plane z = ky that includes the x-axis each grid curve is a circle of radius (1 − |u|) in the horizontal plane z = u each grid curve is a circle of radius |u| in the horizontal plane z = sin(u) the grid curves lie in the vertical plane y = (tan3(u))x