You need to install ActiveX plug-in to be able to view this model.
The model illustrates the main trapezoid properties and parameters .
A trapezoid can be specified by means of a figure which provides to change the locations of trapezoid's vertices by the Mouse. In so doing, the values of trapezoid's elements (the sides, the angles, the altitude, the midline, the area, the circumradius and the inradius) are displayed.
In a trapezoid one can show as follows: the altitude, the midline, the prolongations of the lateral sides, the incircle and the circumcircle, the diagonals. For this to happen, it is sufficient to tick off chosen windows.
Notice that in order for a circle should be inscribed into or circumscribed about a trapezoid, defined conditions should be satisfied.
If a circle cannot be inscribed into a chosen trapezoid (or that cannot be circumscribed about it), this will be shown in the model window.
You can download it here.