把复数=((cos dfrac {2pi )(9)+isin dfrac (2pi )(9))}^3转化为三角形式A =((cos dfrac {2pi )(9)+isin dfrac (2pi )(9))}^3B =((cos dfrac {2pi )(9)+isin dfrac (2pi )(9))}^3C =((cos dfrac {2pi )(9)+isin dfrac (2pi )(9))}^3D 以上都不对

πm·s^(-1))=dfrac (dy)(dt)=Rtdfrac (2pi )(T)cos dfrac (2pi )(T)ti+ndfrac (2pi )(T

sqrt (2)pi -|||-C. dfrac (sqrt {2pi )}(4)-|||-D. dfrac (sqrt {2pi )}(8)

dfrac (2pi )(sqrt {3)} D. dfrac (pi )(6)

dfrac (2pi )(sqrt {3)}-|||-D. dfrac (pi )(6)

(B) dfrac (9)(2pi {c)_(0)(y)^2} - y↑-|||-(0,y)-|||-+q-|||-(C) dfrac (qa)(2pi {va

U=0 (B) E=0 , =dfrac (9)(2pi {varepsilon )_(0)a} q q-|||-(C) =dfrac (q)(2pi {var

(B) dfrac (9)(2pi {c)_(0)(y)^2} - y 个-|||-P(0,y)-|||-+q-|||-(C) dfrac (qa)(2pi {

9.计算下列积分:-|||-(1) (int )_(0)^2pi dfrac (1)(5+3sin theta )dtheta ;-|||-(2) (int

dfrac (qQ)(4pi {varepsilon )_(0)l} C. dfrac (qQ)(2pi {varepsilon )_(0)l} D. -dfr

U=0-|||-(B) E=0 . =dfrac (q)(2pi {varepsilon )_(0)a}-|||-(C) =dfrac (q)(2pi {var