Optical Illusions Small 320×141 Medium 640×283 Large 1024×452 Download Tiff Original 2400×1060 | (154.9 KB) Description Illustration showing optical illusions. It is not always possible to trust the eye to be sure if the lengths of lines a and b are the same. You would need to measure to be sure of your conclusion. Keywords geometry, illusions, lengths, lines, measure, measurement, optical illusion Galleries Visual Illusions Source: C. A. Hart & Daniel D. Feldman Plane And Solid Geometry (New York: American Book Company, 1911) 21 Courtesy the private collection of Roy Winkelman
