QUESTION 1)

(1+i)(1+2i)(1+3i)........(1+ni)=A+iB

show dat : tan^-1(1)+tan^-1(1/2)+tan^-1(1/3)..........tan^-1(1/n)=tan^-1(B/A)

QUESTION 2)

if x=Cos a +i Sin a;y=Cos b+i Sin b;z=Cos c +i Sin c,prove dat

(1)1/x+1/y+1/z=0 whenevr x+y+z=0

(2)xy+yz+zx=0 weneva x+y+z=0

(3)xy/z+z/xy=2cos(a+b+c)

ok basicaly al i noe is u shud use complex numbr properties..

so plzzzz help