Cabri Express Guide

Cabri Express is a webapp like environment, allowing any individual from 5 to 95 years to quickly and simply perform any math operation as a simple calculation, display the graph of a function or construct a figure in 2D or 3D.



At the start, it has a movable calculator. This is a minimalist yet powerful calculator. From the moment you enter a computable expression, the result appears below the expression. The result is preceded by a sign = or a sign  as it is displayed exactly or approximately.

By successively pressing the keys 1 then, ÷ and 2 the fraction 1/2 is obtained and the result 0.5 (with a comma depending on the choice of the system). When clearing the 2 (key )and pressing 3 the result is displayed as ≈ 0.33, because the current display is rounded to 2 decimal places. By pressing keys ^,  or v located at the top right you can change the number of decimal places displayed.

 The presence of the sign ? indicates that the unit waits at least one additional data to perform a calculation.


Please note that the calculator does not contain radian / rocker degree! If you want to calculate sinus 30 ° must indicate that 30 relates to degrees by pressing the button ° He will appear sin 30 ° and the = 0.5 result.If you type sin 30, with no unit indication  the result ≈ - 0.99 appears. Naturally sin π gives as result  = 0.

Parentheses can be used in a calculation but generally Cabri Express requires that parentheses mathematically necessary input and output. To calculate sin (π / 2) and get the result  = 1, it is necessary to type parentheses around π / 2, otherwise we calculate (sin π) / 2  and get  = 0.

Pressing the key alt gives access to a second set of functions to cover all the traditional mathematical functions.



The key y = will automatically graph any function given by an algebraic expression. As soon it is pressed, an axis system appears and as well a new key  x. The graph of the function which has been entered expression is displayed in the axis system that can be modified on demand: just click on a scale tick to drag and change the factors scale in x and y. One can also change the position of the graph, change its bounds as well as the tilt of the axes.

Clicking again y = make possible to display additional graphs with different colors.


Construction in 2D and 3D

Closing the calculator or moving it away, shows on the left a number of different button piles. A simple click on a button selects the corresponding tool. For example pressing the button  will create a line segment by clicking successively in two places to specify the location of both ends of the segment. The most common tools are immediately available, but Cabri Express offers many other tools, which show, by category in using a long click, or by clicking on the right of any pile.

The rectilinear elements of construction tools are e.g. as follows: .


The top pile (or stack) contains management tools . With Cabri, usually it is not necessary to return the Pointer to move items: basically any movable object can be dragged at any time!

If we chose a 3D tool (or the Compass tool) it can be interesting to "tilt" the 3D view by right-clicking or slipping two fingers on tactile screen (such as a tablet).

Double-clicking of an object (a point, a lines, a polygon, a polyhedron,...) displays a palette allowing for color changes :. Double-clicking on a number value allows for changing its display precision.

If a construction requires the repeated use of the same tool, to select it by double clicking makes it "multi-shots" and colors its background in yellow-orange: .

Finally when a pile is deployed one can obtain for each tool, in clicking on it, its name in full and displayed in big (to be readable from the back of the classroom…):


Communication between the calculator and the building elements (geometry)

It is possible to feed the calculator with numeric values from a construction. Below, one clicked with the open calculator successively on the number 5.75 measuring the length of the side [AB] of the rectangle ABCD, then the measure of the length of [AD]. In the calculator the number 5.75 is displayed as 5.75 ... to indicate that this value is approached. The product of the two measures gives the approximate result  ≈ 9.59 cm2 with the explicit mention of the unit.

One can then get the result on the screen by dragging and dropping and compare it to the value displayed directly with the "Area" tool.

In the above example if one moves the cursor Alg⟷  Num to Alg the display 5.75... x 1.75...  becomes  ab  to represent algebraically the calculation process.

In the express toolbar, located at the top of the window, the three icons on the left are for the Creation of a new document, the Opening of an existing document (locally) and the Saving of the current document:  . It is saved in the default Download folder used by the browser. The 4th icon makes possible to reset the view, displaying the worksheet as viewed exactly from above.

Note: Accessing Cabri Express directly from its URL  / one can have Cabri in some different languages, rather than using the current language of the browser. Following languages outside English and  waiting for others, are currently available French, Spanish, German, Dutch (Belgium and Holland), Italian, Greek and Korean. For this add in the URL the language code for examples  fr, en, es, de, it, el, nl ou ko. One can also add a country code to distinguish Belgium from Holland e.g. BE or NL:  https://cabricloud/cabriexpress/?lang=nl-NL .

With smaller kids consider using the “primary” version of Cabri avoiding any more advanced mathematical concepts. The primary version can be found on this url: