(2)s= (3)=√n(xy) (4)2=sin(xyHcos (rv (5):=In tan (6)z=(1+xy)2; (8)arctan(t-1 2.设7=2g,试证(m+8 =0 3.设 求证x2+y2=2z a a 4.设f(xy)=x+(y-) arcsin,x,求f(x,D x2+ 5.曲线=4在点(2,4,5处的切线与正向x轴所成的倾角是多少? 4 6.求下列函数的9,02.02 av2 axa (2):=arctan=' 7.设fx,y,)xy2+12+x2,求质(0.,0,1),(1,0,2,0,-1,0) 及2(2,0,1 8.设z=m),求C及 ar2