钢杆的圆截面上作用有轴力N,弯矩My,扭矩T。若已知许用应力[σ],截面积A,抗弯截面系数W,正确的强度条件为______。

. _(Y)(y)=dfrac (1)(2sqrt {2pi )}(e)^-dfrac (y{2)} ,gt 0-|||-bigcirc ._(Y)(y)=d
πm·s^(-1))=dfrac (dy)(dt)=Rtdfrac (2pi )(T)cos dfrac (2pi )(T)ti+ndfrac (2pi )(T
+(X)_(m))}(sqrt {{{Y)_(1)}^2}+({Y)_(2)}^2+... +({Y)_(n)}^2}} 服从t分布,则 dfrac (m)(n
=dfrac ({n)^2h}(8m/{s)^2}-|||-B omega =(x)=sqrt (dfrac {2)(t)}sin (dfrac ({n)^2p
sqrt (2)pi -|||-C. dfrac (sqrt {2pi )}(4)-|||-D. dfrac (sqrt {2pi )}(8)
(B) dfrac (9)(2pi {c)_(0)(y)^2} - y↑-|||-(0,y)-|||-+q-|||-(C) dfrac (qa)(2pi {va
._(M)-(U)_(N)= -dfrac ({mu )_(0)lg g}(2pi )tln dfrac (a+l)(a) ___ o
(B) dfrac (9)(2pi {c)_(0)(y)^2} - y 个-|||-P(0,y)-|||-+q-|||-(C) dfrac (qa)(2pi {
设(X,Y)的分布函数为(x,y)=dfrac (1)({pi )^2}(dfrac (pi )(2)+arctan dfrac (x)(2))(dfrac (
dfrac (2pi )(sqrt {3)} D. dfrac (pi )(6)