You select three points in the space above, it will mark these points in red, when clicked, can be dragged by changing their placement.
After selection, two figures will be defined: yellow circle and a parallelogram in blue.
The 'reset' button, just below the selection space, resets the buttons, allowing new three buttons to be selected.
On the left we have the information of the coordinates of the points, plus the coordinates and areas of the circle and parallelogram figures.
The last point that is set after the selection of the first three cannot be dragged.
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Our tests were conducted in Google Chrome and Firefox on MacOs and Windows 10.
We try to use vanilla Javascript and defining doesn't use any external library or package. We decided doesn't use any external library or package.