# Question:Graphs in the Question Designer

## Question:Graphs in the Question Designer

I am trying to design a question, where studenst have to find the equation of a linear function given its graph. For this to work, I have to be able to draw gridlines, which for some reason is not possible in Maple TA with the ordinary plot function. I know it should be possible using an applet; given the problems this is going to create with all the different browsers, however, this is not a viable solution. I have found another solution which is unreasonably complex but should work. The problem is that sometimes it doesn't work. When I press Refresh algorithm preview in the Question Designer I get "Broken Maple plot. Verify your plot statement" roughly every third time I refresh the preview. Any help would be greatly appreciated.

The algorithm is here:

\$a1=range(-4,4,1);
\$a2=range(1,4,1);
condition:not(eq(\$a1,\$a2));
\$px=range(0,5,1);
\$y0=range(0,5,1);
\$x0=if(gt(\$a1,0),\$px,-\$px);
\$f=\$a1/\$a2*(x-\$x0)+\$y0;
\$G=plotmaple("
plots[display](
[plots[coordplot](cartesian, [-10 .. 10, -10 .. 10], grid = [11, 11], color = grey),
plot(\$f, x = -10 .. 10, y = -10 .. 10, color = [green, blue, red], thickness = 2, tickmarks = [[1], [1]], labels = [``, ``]),
plots[textplot]([0, 10, 'y'], align = {above, right}),
plots[textplot]([10, 0, 'x'], align = {above, right})
],
labels = [``, ``], axes = normal, view = [-10 .. 10, -10 .. 10]),
plotoptions='width=350,height=350'");
\$g=gcd(\$a1,\$a2);
\$at=\$a1/\$g;
\$an=\$a2/\$g;
\$a=if(eq(\$an,1),\$at,\$at/\$an);
\$ans=\$a*x+(\$y0-\$a*\$x0);

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