I TT

(3) dn(/iM) = (-!)"•' 7-T7:7\«'-ill^"("-^^!J^.^)'

[ji = o, /'i, A-j, . . . , /•„, ; V = o, ri, /'î, . . . , /■«-! I . en particulier ri=^ 1, r>i = ^, . . ., r,i-i— 9.{n — c)J

sn^u

(4) sninu) = nsnu~[l , ^., .X^^^v'sn^^'

dn2a|j.,v sn^a

(5) cn(wa)^cim]~J-^^^ J

(6) dn(/iM) = dnw I I

dn^aj^^^

/:2 sn^aii.v sn^M

(7) 7vfp-r= n^"'«^'-

(9) (v//7)"'"*=fjdn2aj,,„

'[x = O, V = ri, rj, ••.,r„i

fi^n, /-î, ..., r„i, v = o, zbn, ±r2, ..

FORMULES. 299

XC (fin).

(10) n snC/m) = / ^ sn(tf -+- iar,s),

(il) (— 1) " /t cn(/m) = / ^ cn{u -\- iar,s),

r — /'o, /'i, . • . , r„i ; 5 = 5o) *i) • • • ) *«-i en particulier : r^ — «o = 0, /"i = S| = i , . . . , /•„i = s,i-\ ^= n — i