空间曲线 $\begin{cases} x = t \cos t \\ y = t \sin t \\ z = t \end{cases}$, 当 $t = \pi$ 时, 对应点的坐标为 ().
A $(\pi, 0, \pi)$;
B $(-\pi, \pi, \pi)$;
C $(0, 0, \pi)$;
D $(-\pi, 0, \pi)$
f(x)= pi ,dfrac {pi )(2)lt xlt pi (D)0
3.要使函数φ(x )= ,dfrac {pi )(2)] (B)[π,2π] (C) [ 0,dfrac (pi )(2)] (D) [ dfrac
[ 0,dfrac (pi )(2)] D. [ -sqrt (dfrac {pi )(2)},0]
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)
dfrac (pi )(3)B . dfrac (pi )(3)C . dfrac (pi )(3)D . dfrac (pi )(3)[单选题]复数1+i对应
dfrac (1)(2)pi .-|||-C.π-|||-D. dfrac (5)(4)pi .-|||-0
3【单选题】辐角主值的范围是A、,pi ] B 、,pi ] C、 ,pi ] D、,pi ]3【单选题】辐角主值的范围是A、 B
(int )_(-pi )^pi sqrt ({pi )^2-(x)^2}dx= )(int )_(-pi )^pi sqrt ({pi )^2-(x)^2}d
(B) dfrac (lambda )(2pi {varepsilon )_(0)a}. (C) dfrac (lambda )(4pi {varepsilon
(B) pi +dfrac (4)(3) (C) pi +2 . (D) pi +dfrac (8)(3)