Sketching Construction Lines Click Isometric (Standard Views toolbar). Click Plane (Sketch toolbar) and in the PropertyManager, do the following: Select Front Plane for First Reference. Select Coincident , and then click . Click Centerline (Sketch toolbar), and use inferencing to sketch a vertical construction line coincident to the mid point of the tangent arc. Clear the Centerline tool. Sketch a construction line perpendicular to the existing construction line that spans the circle. Parent topic3D Sketching with Planes Previous topic Completing the Addition of Curvature Next topic Fully Defining the Geometry