Drag the vertices of the triangle. As long as they are not all three on the same line, the shape is a triangle.

Check out the [url=https://www.geogebra.org/m/vQczcjyW]GeoGebra book for learning how to recognize, name and sort the geometric figures rectangle, square, triangle and circle and practice in a real life context[/url]. We will give an example as soon as it is possible.