证明:当 lt xlt dfrac (pi )(2) 时, tan xgt x+dfrac (1)(3)(x)^3.

证明下列不等式:-|||-(4)当 lt xlt dfrac (pi )(2) 时, tan xgt x+dfrac (1)(3)(x)^3 ;

[题目]-|||-证明:当 lt xlt dfrac (pi )(2) 时, sin x+tan xgt 2x

5.证明下列不等式:-|||-(3)当 lt xlt dfrac (pi )(2) 时, sin x+tan xgt 2x ;

设(x)=((2-x))^tan dfrac (pi {2)x},(dfrac (1)(2)lt xlt 1),求(x)=((2-x))^tan dfrac (

、证明:当 -1lt xlt 0 时, arcsin sqrt (1-{x)^2}-arctan dfrac (x)(sqrt {1-{x)^2}}=dfrac

证明:当 gt 0 时,有不等式 arctan x+dfrac (1)(x)gt dfrac (pi )(2)

(8) lim _(xarrow dfrac {pi )(2)}dfrac (tan x)(tan 3x)

(8) lim _(xarrow dfrac {pi )(2)}dfrac (tan x)(tan 3x)

1357.已知 tan x=1, in (dfrac (pi )(2),dfrac (3pi )(2)), 则 =-|||-

3.证明: (int )_(x)^1dfrac (dt)(1+{t)^2}=(int )_(1)^dfrac (1{x)}dfrac (dt)(1+{t)^2}