The shearing stress in a rivet depends on the load transmitted and the shear area. The shear area depends on whether the rivet is in single shear or double shear. The phrasing "three steel plates are held together by a rivet" can be ambiguous, but in many contexts, it implies double shear, meaning the rivet experiences shear on two planes. However, if it refers to a simple lap joint, it would be single shear. The calculation requires the area of the rivet and the number of shear planes.