Since A lk is a determinant we similarly obtain Alk = a21Alk+ï¿½ ï¿½ ï¿½ +a2,k-iAl,k +a2,k+lAl,k+ ï¿½ï¿½ï¿½+a2 21 2,k-1 2, k +1 2,n and thence = Xalia2kAli where k; i,k 2k and as before A = a1, an A i> k i,k I ail, auk 12k an important expansion of A.
Of the area A, f f xdxdy = o, ffydxdy = 0, (6) R = p hA, (7) xhA = - cos a f f x 2 dA - sin affxydA, fxydA, (8) yhA = - cos a ff xydA - sin ail y 2 dA.
O16u3) If we replace 440136u3 in this expression by g405 6 u 3, the method of § 68 gives A -Q AIL h (uo + 5 u 1 + u2 + 6u3 + u4 + 5 14 6 + us); the expression on the right-hand side being an approximate expression for B, and differing from it only by s1eH5 6 u 3.
4c men fOatfrcryteyou/anbper(ccutc you/ artb O at f at f iy f:ayc ail of a e 141.'101 a i lay'tlrt you 1,-.r fly cioyc+t all arc u)youre rc roHr =' FIG.