( 497 ) 
ger 
L(e + ea) = = sin @ sin (w sin g + asin p) dy 
Xt 
0 
follows 
Sade 
I,(@—a +L (we +e) = =) sin p sin (a sin p) cos (a sin p) dp. 
x 
0 
If we write 
sin (a sin gp) = 2 I, sng + 21, sin Sp +. 
we obtain 
4 
L(«—-a+hwt+a=—-Jf of so p cos (a sin p) dp 
I 
0 
4 Peon | 
+ — I, (x) | sing sin 3p cos (a sin p) dp 
x 
sin p sin 5@ cos (a sin yp) dip 
+ 
En 
n 
+. 
or as 
2 sin p sin (2n + 1) p cos (a sing) dp = 
0 
= fes 2np — cos (2n + 2) y] cos (a sin 7) dip 
= a [Lon (@) — Tan 42 (@)] 
gh: d Tan 41 (@) 
da 
we get 
I, (@—a)+1,(@+a)= aE ‘+ 1, () ELD | 
Substituting here 7 
dI,, 
= =n TI, (a) — a Ini (a) 
we arrive finally at 
4 ® 
I, (e—a)4+ 1, (e +e)= = Sn I, (a) ZL (a) — 4 > Ln +1 (a) Zo (2). 
