Creating the Third Spline Click Spline (Sketch toolbar). Sketch a two-point spline coincident between the end point of the vertical construction line and the horizontal construction line just added. Click Add Relation (Dimensions/Relations toolbar). In the graphics area, select the spline and the vertical construction line. In the PropertyManager, under Add Relations, click Tangent , then click . Parent topic3D Sketching with Planes Previous topic Fully Defining the Geometry Next topic Completing the Third Spline