38 
MEMO RI AS CIENTIFICAS I LITER ARIAS 
X cl 
(Sonnet, 232) 
7. Otro metodo. (Frenet, 252). 
/ tg 2 x dx = / (sec 2 x — l)d x = tg x — x . 
= — cot X— X. 
9. Otro metodo. 
/ x cot 2 x=/ x (cosec 2 x— 1)= — cot x - x. 
0. f sen 2 m x = — [ (1 -cos 2 m x) d m x 
ix m J 
1 — sen 2 x 
x sen 2 x 
(2 m x— sen 2 m x) 
4m 1 i ' 
(Perry, 364) 
11. f cos 2 n x d x = 
n 
J cosfn x d n x 
