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. 1 ( ( ) ) . . (1781-1868) , ib ( ), (n21 - ), ( , ) (. 2). iB , . , (tgiB = siniB/cosiB, n21 = siniB / sini2 (i2 - ), cosiB = sini2). , iB i2 = p/2, i¢b = iB ( ), i'B + i2 = p/2. , ( ). ( ). , , (n = 1,53) 15%, 8-10 . . , .
14: , - . , , , . . . 1810 .
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