. . . . . . . "Euclid's" . . . . . . . . . . . . . . . . . . . . . . . "Optics" . . . . "Euclid" . . "Eukleid\u0113s" . . . . "Euclidis" . "mathematician" . "ancient Greek mathematician" . . . . "Eukleides of Alexandria" . . . . . . . . . . . . . . . . . . . . . "writer of ''Elements''" . . "Greek mathematician" . "Greek Mathematician" . . "Euclid's formula" . . . . "Euclid" . . "Euclid's ''Elements''" . . . "Father of Geometry" . . . . . . "found" . . . . . . . . . . . . . . . . "EUKLID" . . . . . . . . "\u0395\u1F50\u03BA\u03BB\u03B5\u03AF\u03B4\u03B7\u03C2" . . . . . . . . "Euklidis" . . . . . . . "wrote extensively" . . . . . "Euclid of Alexandria" . . . . . . "the mathematician" . . . . . . . . . . . . . . . .