Take 2: Transfer slope to graph from table input

Sorry I posted the wrong link from my last question.

I am having difficulty getting the following to happen on slide 7:

I want students to input a numeric value into a table. I want the graph component to pick up that input as a numeric value, and graph a small section of that line around the given point. This way students can see how their slope at particular point matches the slope field.

Ex: For the point (-4,2) the slope is -4, or the point (0,4) has a slope of 0.

Hmm from what I’m seeing, you should be good:

number(`m_1`):t1.cellNumericValue(1,3) is going to pass down the first point’s slope (1st row, 3rd column) into the graph, where line 6 is ready to graph a section of the line with that slope: y=m_1(x+4)+2{-4.02<x<-3.98}.

I might tweak that condition to be {distance((x,y),(-4,2)<0.3} so that the overall length of the line stays the same even with extreme slopes, but it feels like you just need some copy-paste-replace for the other rows of the table!

For a bit more robustness, though, here’s an alternate to your graph: https://www.desmos.com/calculator/vjoa7yvooi. It uses a polygon for each line segment, which can be a little bit faster for the calculator to draw, and also supports vertical lines for undefined slopes. For the “Multiple Points” folder, I replicated the logic of the Slope Field folder to get a d_rawSegmentWithSlope helper, and set it up to know about the m1 through m6 variables you’d be passing down via CL. (I’m imagining in the case of und from the student, you could pass down \frac{1}{0}.)


Thanks for the help. I really appreciate the alternate graph, and like the way you can adjust the r value for a different radius. By seeing your example I realize the line was actually showing up, but changing the thickness allows you to see the line. I was able to copy the drawsegmentwith slope into the graph and everything worked well.

I like the condition to make the overall length of the slopes stay a set amount, but I couldn’t get that to work on a linear equation the way I normally adjust the domain or range. Is that just something that works with the polygon feature, or is that something I should be able to adjust at the end of a function?

I think you need
distance((x,y),(-4,2))<0.3 (note that the “outside” brackets start after distance and finish after the second coordinate).