Part Modeling > Tweak Features > Ears > About Ears
  
About Ears
When you sketch an ear, remember the following rules:
The sketching plane must be perpendicular to the surface to which the ear will be attached.
The section for the ear must be open with the endpoints aligned to the surface to which the ear will be attached.
The entities that are attached to the surface must be parallel to each other, perpendicular to the surface, and long enough to accommodate the bend.
The radius of the bend is measured from the sketching plane out of the screen.
The ear is bent at the specified angle, measured from the surface from which the ear is extruded. The ear bends towards you, out of the screen, and is extruded into the screen to the specified thickness.