Toggles the Perpendicular Snap on or off. When set to ON, you can snap a new entity that you are drawing to point perpendicular to another entity. You can snap a new entity to a point perpendicular to an arc, circle, line, Polyline, and infinite line. To use this choose 'Settings Menu > Snap > Perpendicular snap' or select icon from snap toolbar.
To use Perpendicular snap