Concave Square Optical Illusion

This example demonstrates a geometric optical illusion where a flat square appears to be concave. The construction involves core mathematical concepts of planar geometry, symmetry, and visual perception. It is built using GeoGebra's 'Circle' command to define precise anchor points and the 'Sequence' command to generate repetitive geometric patterns, utilizing objects such as circles (k, c) and line segments (l1, l2) to create the illusion. This resource is ideal for middle school geometry students exploring geometric transformations or for educators demonstrating the intersection of mathematics and visual arts.