This Graph menu command changes the grid appearance and scaling of the marked coordinate system. Sketchpad’s coordinate systems can have several possible forms: 
Polar Grid: A polar coordinate system has a set of grid lines that are circles (at a constant distance from the origin, or r value) and a set of grid lines that pass through the origin (at a constant angle from the origin, or θ value). Any coordinate system can be made polar. If the horizontal and vertical axes of a polar coordinate system have different scaling, the constantdistance grid lines appear as ellipses rather than circles. 
Polar 
Square Grid: A square coordinate system has the same scaling on the horizontal and vertical axes and has grid lines that are horizontal (at a constant y value) and vertical (at a constant x value). Any coordinate system, except one defined in terms of two different distances, can be made square. 
Square 
Rectangular Grid: A rectangular coordinate system has independent scaling for the horizontal and vertical axes and has grid lines that are horizontal (constant y value) and vertical (constant x value). Any coordinate system, except one defined in terms of a unit circle, can be made rectangular.

Rectangular 
Trigonometric Axis: The horizontal axis is numbered with fractions and multiples of π. You can use a trigonometric axis on any kind of coordinate system. When you choose trigonometric axes for a polar grid, both axes become trigonometric. You can turn trigonometric numbering on or off for any axis by selecting it and choosing Edit  Properties  Axis.

Square with Trigonometric Axis 
If you choose one of these commands with a sketch that doesn’t yet have a coordinate system, Sketchpad creates a default coordinate system with the chosen form.
See also: