Akdu uɣmir i kra n tfekka d akdu imeẓri n tfekka seg kra n wadeg yettwakten d tiɣmert. Akdu uɣmir yettusemres deg tesnallunt i wakken ad imel akat n tfekkiwin deg tallunt Tiftarin tusnakin Asiden n ukdu uɣmir n kra n talɣa d ayen izemren ad yili s usemres n wassaɣ: δ = 2 arctan ⁡ ( 1 2 d / D ) , {\displaystyle \delta =2\arctan \left({\frac {1}{2}}\,d/D\right),} Anda δ {\displaystyle \delta } ukdu uɣmir d {\displaystyle d} d D {\displaystyle D} d akdu imeẓri d westum ɣef tfekka yettwaktan s yiwet n tigget ya mi ara ad yili D {\displaystyle D} yugar s waṭas d {\displaystyle d} , d ayen izemren ad yili usades n watig δ {\displaystyle \delta } s wassaɣ δ = d / D {\displaystyle \delta =d/D} anda atig n tiɣmert tettwaket s uradyan. I lment n tfekkiwin timezzayin ilan (yesɛan) akdu-ines imdetti yegda d act {\displaystyle d_{\mbox{act}}} akdu uɣmir yettwafk-d s wassaɣ: δ = 2 arcsin ⁡ ( 1 2 d act / D ) . {\displaystyle \delta =2\arcsin \left({\frac {1}{2}}\,d_{\mbox{act}}/D\right).} Ẓeṛ daɣen == Imniren ==