[" im "(cos(tan x)-cos x)/(x^(4))=],[[rarr0," (b) "-(1)/(2)," (c) "-(1)/(6)]]

int((tan x)/(cos x))^(4)dx

lim_ (x rarr0) (cos (tan x) -cos x) / (x ^ (4)) =

lim_(x rarr0)(cos(tan x)-cos x)/(x^(4)) is equal to :

cos ^(-1) ""((cos x + cos y)/(1+cos x cos y))= 2 tan ^(-1) (tan ""(x)/(2) tan ""(y)/(2))

int(1+cos4x)/(cot x-tan x)dx

int(1+cos4x)/(cot x-tan x)dx

lim_(x rarr0)((1-cos2x)(3+cos x))/(x tan4x) =

int(tan(3+4x))/(cos(3+4x))dx :

prove that tan ((pi) / (4) + (1) / (2) cos ^ (- 1) ((a) / (b))) + tan ((pi) / (4) - (1) / (2) cos ^ (- 1) ((a) / (b))) = (b) / (a) cos ^ (- 1) ((cos x + cos y) / (1 + cos x cos y) ) = 2tan ^ (- 1) ((tan x) / (2) (tan y) / (2))