This introductoty file contains general information for all the graphic files in this selection.

The technology used for the graphics, is SVG (Scalable Vector Graphics), allowing animations and interactivity. Animations can be started, paused, resumed, speeded up and down. The scalability allows to zoom-in, zoom-out, and pan any detail. Yellow rectangles or circles are used as interactive buttons.

The SVG files display graphical information and text. The extensive use of colours in the graphics, also appears in the text. We have attempted to match the colour of the text with the appropriate detail in the graphics, in order to focus the attention of the user to that particular detail.

The title appearing in any graphical file represents also a link back to the correspoding introductory page.

The well known Pythagorean theorem for a right-angle triangle is formulated by the following expression:

${c}^{2}={a}^{2}+{b}^{2}$

where c is the length of the hypotenuse, and the symbols a and b - of the other sides.

The SVG file Fig. Pythagoras corresponding to the present introductory file, contains additional general information together with a proof of the popular Pythagorean theorem.