[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 ;

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 ;

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

(sin x)=dfrac (1)({cos )^2x} in (0,dfrac (pi )(2)),则(sin x)=dfrac (1)({cos )^2x}

计算 lim _(xarrow dfrac {pi )(2)}dfrac (ln sin x)({(pi -2x))^2}

求lim _(xarrow dfrac {pi )(2)}dfrac (ln sin x)({(pi -2x))^2}求

lim _(xarrow dfrac {pi )(2)}((sin x))^tan x=（ ）（ ）

( (int )_(dfrac {pi )(4)}^dfrac (pi {3)}dfrac (x)({sin )^2x}dx ;

[题目] lim _(xarrow 0)(dfrac (1)({sin )^2x}-dfrac ({cos )^2x}({x)^2})= __