求极限 lim _(xarrow 1)dfrac (ln [ cos (x-1)] )(1-sin dfrac {pi )(2)x}
[题目]曲面 =(x)^2(1-sin y)+(y)^2(1-sin x) 在点(1,0,1)处-|||-的切平面方程为 __
9.求曲面 =(x)^2(1-sin y)+(y)^2(1-sin x) 在点(1,0,1)处的切平面方程.
已知sin（α-β）=(1)/(3)，cosαsinβ=(1)/(6)，则cos（2α+2β）=（ ）A. $\frac{7}{9}$B. $\frac{1}{
(int )_(0)^12xcos ((x)^2+1)dx= ( )A.cos 2- cos 1B.cos 2+ cos 1C.sin 2- sin 1D.si
1.[论述题] 0202 证明：cos z=cos xcos y-sin xsin y.1.[论述题] 0202 证明：$\cos z=\cos x\cos y
[单选题] sum _(n=0)^infty ((-1))^ndfrac (2n+3)((2n+1)!)=A.sin1+cos1B.2sin1+cos1C.2s
pni = IS = — BSwosin cot ;〃 R(2) M = Bp sin cot = — BSa)sin cot,f 移汗 1 9 9
lim _(xarrow 0)cot x(dfrac (1)(sin x)-dfrac (1)(x))= __
lim_(xto0)cot x((1)/(sin x)-(1)/(x))=____.(94-1 3分)$\lim_{x\to0}\cot x(\frac{1}{