Perpendicular to Two EntitiesKeyCreator \ Create \ Line \ Perpendicular-to-Two-Entities
Use this feature to create a line perpendicular to two selected entities. Remember that when in 3D construction mode, the selected entities must be coplanar.
NOTE: When using this function, you will not be able to select two linear entities (lines, polylines, and vectors), because there is either nothing perpendicular to both of them, or that which is perpendicular to both of them is a plane, and not a line.
Using the Function: