GraphingCalculator 3.2;
Window 44 6 611 390;
PaneDivider 250;
FontSizes 12 9 9;
2D.BottomLeft -1.96875 -2.90625;
Color 5;
Expr sin(a*pi*x)*sin(a*pi*y)=0;
Expr a=4;
Text "To make the background grid darker so that is shows up more clearly on printout or on an overhead projector, you can graph an implicit equation whose solutions are the grid lines. We can then choose
the color in the popup menu by the equation. For different zoom levels, you would have to adjust the value of a so that the solutions coincided with the grid lines.
By copying and pasting these equations into other documents, they will have the same effect there.";