可以使 (x)=-sin x 成为概率密度的x取值范围是 ()-|||-(A) [ -pi /2,0] ; (B) [ 0,pi /2] ;-|||-(C) [ -pi /2,pi /2] ; (D) [ -pi /2,3pi /2] .

设随机变量UND的概率密度函-|||-(x)= dfrac {2)(pi )(sin )^2x,-dfrac (pi )(2)leqslant xleqsl

3.要使函数φ(x )= ,dfrac {pi )(2)] (B)[π,2π] (C) [ 0,dfrac (pi )(2)] (D) [ dfrac

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

f(x)= pi ,dfrac {pi )(2)lt xlt pi (D)0

设 M=int_(-(pi)/(2))^(pi)/(2) (sin x)/(1+x^2) cos^4 x dx，N=int_(-(pi)/(2))^(pi)/(

设(x)=sin x, 则(dfrac (pi )(2))= __-|||-_.-|||-A cos dfrac (pi )(2)-|||-B o-|||-C-

(int )_(-pi )^pi sqrt ({pi )^2-(x)^2}dx= )(int )_(-pi )^pi sqrt ({pi )^2-(x)^2}d

设随机变量X的概率密度为f(x)=}kcos x, & |x|leq(pi)/(2),0, & |x|>(pi)/(2).则k等于( ).A. $\frac{

(15) lim _(xarrow pi )dfrac (sin 2(x-pi ))(x-pi );

1.设 (x)=sin x 是某个连续型随机变量X的概率密度函数,则它的取值范围-|||-是 () .-|||-(A) [ 0,dfrac (pi )(2)]