Using a steel square to check the flatness of a wall corner is not possible. The main purpose of a steel square is to mark and measure right angles in woodworking and carpentry, rather than determining the flatness or levelness of a surface. For assessing the flatness of a wall corner, it would be more suitable to use a level or a straightedge. A level will indicate if the wall corner is straight and plumb, while a straightedge can be employed to detect any gaps or irregularities in the surface.
No, a steel square cannot be used for checking the flatness of a wall corner. A steel square is primarily used for marking and measuring right angles in woodworking and carpentry. It is not designed to determine the flatness or levelness of a surface. To check the flatness of a wall corner, a level or a straightedge would be more appropriate tools. A level will indicate whether the wall corner is straight and plumb, while a straightedge can be used to check for any gaps or irregularities in the surface.
