Pappus Theorem

Points A,C and a,c on the black lines can be dragged by the mouse to new positions, changing the lines through them. The points B and b can be moved as desired on the lines. The red, yellow and blue lines form the sides of an inscribed hexagon, with opposite sides of the hexagon the same color. The cyan line always passes through the three intersections of opposite sides. Note that Pappus theorem is self dual. Press "r" to reset the sketch.

Sorry, this page requires a Java-compatible web browser.