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Affine ratio
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<iframe 
    src="http://jsxgraph.org/share/iframe/affine-ratio" 
    style="border: 1px solid black; overflow: hidden; width: 550px; aspect-ratio: 55 / 65;" 
    name="JSXGraph example: Affine ratio" 
    allowfullscreen
></iframe>
This code has to 
<div id="board-0-wrapper" class="jxgbox-wrapper " style="width: 100%; ">
   <div id="board-0" class="jxgbox" style="aspect-ratio: 1 / 1; width: 100%;" data-ar="1 / 1"></div>
</div>

<script type = "text/javascript"> 
    /*
    This example is licensed under a 
    Creative Commons Attribution 4.0 International License.
    https://creativecommons.org/licenses/by/4.0/
    
    Please note you have to mention 
    The Center of Mobile Learning with Digital Technology
    in the credits.
    */
    
    const BOARDID = 'board-0';

    JXG.Options.label.autoPosition = true;
    JXG.Options.label.fontSize = 24;
    
    const board = JXG.JSXGraph.initBoard(BOARDID, {
        boundingbox: [-5, 5, 5, -5],
        keepaspectratio: true
    });
    
    var p = board.create('point', [-3, 0], {
        name: 'p'
    });
    var q = board.create('point', [3, 0], {
        name: 'q'
    });
    var pq = board.create('line', [p, q]);
    var t = board.create('glider', [-2, 0, pq], {
        name: 't'
    });
    var txt = board.create('text', [1, 2, () => "λ = " + t.position.toFixed(2)], {
        fontSize: 24
    });
 </script> 
/*
This example is licensed under a 
Creative Commons Attribution 4.0 International License.
https://creativecommons.org/licenses/by/4.0/

Please note you have to mention 
The Center of Mobile Learning with Digital Technology
in the credits.
*/

const BOARDID = 'your_div_id'; // Insert your id here!

JXG.Options.label.autoPosition = true;
JXG.Options.label.fontSize = 24;

const board = JXG.JSXGraph.initBoard(BOARDID, {
    boundingbox: [-5, 5, 5, -5],
    keepaspectratio: true
});

var p = board.create('point', [-3, 0], {
    name: 'p'
});
var q = board.create('point', [3, 0], {
    name: 'q'
});
var pq = board.create('line', [p, q]);
var t = board.create('glider', [-2, 0, pq], {
    name: 't'
});
var txt = board.create('text', [1, 2, () => "λ = " + t.position.toFixed(2)], {
    fontSize: 24
});
<jsxgraph width="100%" aspect-ratio="1 / 1" title="Affine ratio" description="This construction was copied from JSXGraph examples database: BTW HERE SHOULD BE A GENERATED LINKuseGlobalJS="false">
   /*
   This example is licensed under a 
   Creative Commons Attribution 4.0 International License.
   https://creativecommons.org/licenses/by/4.0/
   
   Please note you have to mention 
   The Center of Mobile Learning with Digital Technology
   in the credits.
   */
   
   JXG.Options.label.autoPosition = true;
   JXG.Options.label.fontSize = 24;
   
   const board = JXG.JSXGraph.initBoard(BOARDID, {
       boundingbox: [-5, 5, 5, -5],
       keepaspectratio: true
   });
   
   var p = board.create('point', [-3, 0], {
       name: 'p'
   });
   var q = board.create('point', [3, 0], {
       name: 'q'
   });
   var pq = board.create('line', [p, q]);
   var t = board.create('glider', [-2, 0, pq], {
       name: 't'
   });
   var txt = board.create('text', [1, 2, () => "λ = " + t.position.toFixed(2)], {
       fontSize: 24
   });
</jsxgraph>
Affine ratio of three points. The more popular name seems to be *simple ratio*, in German *Teilverhältnis*. It is defined as $$ TV(p, q, t) := \lambda \in K \mbox{ such that } \vec{pt} = \lambda\cdot\vec{pq} $$ 
// Define the id of your board in BOARDID

JXG.Options.label.autoPosition = true;
JXG.Options.label.fontSize = 24;

const board = JXG.JSXGraph.initBoard(BOARDID, {
    boundingbox: [-5, 5, 5, -5],
    keepaspectratio: true
});

var p = board.create('point', [-3, 0], {
    name: 'p'
});
var q = board.create('point', [3, 0], {
    name: 'q'
});
var pq = board.create('line', [p, q]);
var t = board.create('glider', [-2, 0, pq], {
    name: 't'
});
var txt = board.create('text', [1, 2, () => "λ = " + t.position.toFixed(2)], {
    fontSize: 24
});

license

This example is licensed under a Creative Commons Attribution 4.0 International License.
Please note you have to mention The Center of Mobile Learning with Digital Technology in the credits.