On a circle, there is a point that is vertically above the centre and a point that is vertically below the centre. Likewise there is a point is to the left of the centre and to the right of the centre.
What term can be best used to describe these points?
Maximum and minimum points don't seem correct? And these would only apply to the point vertically above and the point vertically below the centre, not the ones on the same horizontal line as the centre.
What about extrema?