Plane trigonometry, by S.L. Loney.

ANSWERS. xxiii
6. S = cot -2 cot 20; =-2 cot 2.
- "1 96.
7. 2 coth 20- coth 2- 8. tan 2 - tan 0.
9. tan9 - tan 0; tan 0... -.. _
10. sin 0 (cot 0 - cot 2n9).
I 1
11 2 sin 28 + (-l)ff+l Z-1 sin 28+l.
12. sin 20- sin 2n+l.
1 9 2n + I1
13. cosec - (sec 2 - sec.
2 2+ 1_e.2
14. Sn = tan 2a-2tana; S =2a-2tana.
15. {3 cos0 ( - ) os 3n }.
16.4 {3- sin -sin.
17. [3ntan 3n -tan ].
18. [cot 0 - 3n cot 3n 0].
19. tan-' {(n+k 1) (n + 2)}-tan- 2.
20. tan- (n + 1) - tan- 1, i.e. tan"'l -
n +2'.7
21. iS tan-' 2 - tan-1 1; S - -.
1 7r
22. = sin- 1 - sin-l 1; S =
LXIII. (Pages 421, 422.)
1. 1-acos + a2 cos -20-a cos 3 +... ad inf.
2. cos 9 + a cos ( + + )+ a cos (0:+ 20) +....ad inf.