Aqqaṛ d azgen n wekdu n twinest neɣ tsegla neɣ n uglay. Aqqaṛ yegda amaccaq yebṭan gar n wammas n twinest ( neɣ tsegla neɣ n uglay) de yal agaz deg tlisa n telɣa. Aqqaṛ yegda taseɣleyt yebṭa ɣef 2 Pi ( r = c 2 π {\displaystyle r={\frac {c}{2\pi }}} ). Aqqaṛ n twinest Assaɣ gar n waqqaṛ R {\displaystyle R} d tseɣleyt L {\displaystyle L} n twinest d: R = L 2 π {\displaystyle R={\frac {L}{2\pi }}} . I usiden n waqqaṛ R {\displaystyle R} i twinest i yekkan ɣef 3 n wagazen A , B , C {\displaystyle A,B,C} nezmer ad nessemres taftart-a : R = a 2 sin ⁡ α {\displaystyle R={\frac {a}{2\sin \alpha }}} , neɣ a {\displaystyle a} est la longueur B C {\displaystyle BC} et α {\displaystyle \alpha } akat n tɣmert B A C ^ {\displaystyle {\widehat {BAC}}} . Ma ttwanefken 3 n wazagen s yimsidag-nsen ( x 1 , y 1 ) {\displaystyle (x_{1},y_{1})} , ( x 2 , y 2 ) {\displaystyle (x_{2},y_{2})} d ( x 3 , y 3 ) {\displaystyle (x_{3},y_{3})} , nezmer daɣen ad nessemres taftart-a (voir asaduf n uwsi et Tajumma n ukeṛdis) : Aqqaṛ n uglay Aqqaṛ n uzunglay == Ẓeṛ daɣen ==