Sliders and Movable Points

Getting Started with Sliders

In Desmos, adding a slider is as simple as typing a letter where you might normally see a number. Add movable points, shifting lines, dancing curves, and anything else you can dream up in this intuitive, dynamic math playground. Did we mention animations run at a beautiful 60 fps? Get started with the video on the right, then dive deeper with the resources and challenges below.

Any time you have free variables in an expression, the calculator will offer to let you define them with sliders. You will see the option to add sliders appear in the expression bar once you finish typing in your equation. (Desmos has define e as constant and therefore cannot be used as a slider variable.)

GIF showing y=mx+b using sliders.

 

You can also use the same variables in several expressions to plot curves that will change together. In this example, the value of c defines two parallel lines that move up and down together. In this example, the two lines stay perpendicular to each other for any value of m.

 

Slider Limits, Intervals and Animation Speed

To adjust the limits and interval of your slider, click either of the values at the ends of the slider bar. Input your values and your graph will be automatically updated.

Lower, Upper bounds, and step edit window for sliders. Screenshot.

Adjusting the Animation:

  • Loop forward and backwards
  • Repeat in one direction
  • Play once
  • Play indefinitely
  • Increase and decrease the speed

Animation options to play sliders  . Screenshot.

Dynamic Bounds

You can use dynamic bounds to ensure a slider value stays between two other slider values. Check out this example exploring the Mean Value Theorem.

Graph showing the use of dynamic bounds. Screenshot.

Moveable Points

You can change a static point to a movable point by clicking and long-holding the icon next to the expression list. A style editor will pop up with different drag options.

Point menu screen.  Shows how to make a point movable.  Screenshot.

Another way to create a movable point is to enter a point with a parameter for one or both coordinates. Click and drag the point around the graph to change the value of the parameter(s).

Animation on how to make movable points using coordinates such as (a,b) with sliders. Screenshot.

To make graphs more interactive, use parameters from your movable point in your expressions.

Explore this graph.

Interactive graph with movable points. Screenshot.

You can create a moveable point along a curve using sliders.

Explore this graph.

Movable point along a curve. Screenshot.

You can also drag a moveable point along a parametric path!

Explore this graph.

Animation showing a point moving along a parametric path. Animation.

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