I

16/|

2, _ 7*

log Cos — log Cos *-"■ + u7/ r fP

log Cos = log Cos-— -J- 3 .'

7, ,i 7p

log Cos — = log Cos— - -f- a" u. s. w..

so ist

a = los Cos — —• log Cos -—

° 3 D s

Z°

= AlogCos —

= “ * T"

wo A z = z — Z*

Ist eben so

A = z* — z°)

A z" = z /7 — z° u: s; w. .$so ist auch

a'=-iAz' Tg

7p

a ;/ = — -i A z"Tg —— u.s.w., also

log /Cos —-Cos— Cos — .. . )— log Cos——)—(a—|—a'—

2 2 2 / ö a n

n

=. log Cos-^i T S “V (Ae + Az' + A2"+)

Z°

= log Cos —

weil A z + Ä z' + A 2 " +

= (z — z°) + (z' — z°) + (z" — z°) +

= Z —• n z°

Has heifst — Z — Z = o ist, so lange man blofs auf <ln' Cl ‘steil Differenzen Rücksicht nimmt.