(int )_(0)^12xcos ((x)^2+1)dx= ( )A.cos 2- cos 1B.cos 2+ cos 1C.sin 2- sin 1D.sin 2+ sin 1

[单选题] sum _(n=0)^infty ((-1))^ndfrac (2n+3)((2n+1)!)=A.sin1+cos1B.2sin1+cos1C.2s

已知sin（α-β）=(1)/(3)，cosαsinβ=(1)/(6)，则cos（2α+2β）=（ ）A. $\frac{7}{9}$B. $\frac{1}{

int dfrac (sin x)(1+{cos )^2x}dx=-|||-__

已知曲线积分(int )_(1)^1(1+dfrac ({cos )^2}({x)^2}cos dfrac (y)(x))dx+(sin dfrac (y)(x

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

)int dfrac (1)({cos )^2x(sin )^2x}dx.

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

1.“sin^2 alpha +sin^2 beta =1”是“sin alpha +cos beta =0”的（）.A. 充分非必要条件B. 必要非充分条件C

(d)/(dx)int_(sin x)^cos x cos(pi t^2) , dt = ( ). $\frac{d}{dx}\int_{\sin x}^{\c

|sin 2|leqslant 1 D. (sin z)=cos z