The yaxis on the wall is vertical but the one on the table is horizontal. In the 2dimension case, as mentioned already, the usual designation of the vertical coincides with the yaxis in coordinate geometry. This convention can cause confusion in the classroom. For the teacher, writing perhaps on a white board, the yaxis really is vertical in the sense of the plumbline verticality but for ...
![](/themes/3fr7/images/logo/logo.png)