If `z_(k)=cos((kpi)/(10))+isin((kpi)/(10))`, then `z_(1)z_(2)z_(3)z_(4)` is equal to

If z_(k)=cos((k pi)/(10))+i sin((k pi)/(10)), then z_(1)z_(2)z_(3)z_(4) is equal to (A)-1 (B) 2(C)-2 (D) 1

If z_k=cos((kpi)/(10))+isin((kpi)/(10)) , then z_1z_2z_3z_4 is equal to

Let z_(k) = cos((2kpi)/(10)) -isin ((2kpi)/(10)), k = 1,2,…..,9

If z=cos((pi)/(3))-isin((pi)/(3)) then z^(2)-z+1=....

If Z_r=cos((2rpi)/5)+isin((2rpi)/5),r=0,1,2,3,4,... then z_1z_2z_3z_4z_5 is equal to

If z^(n) = cos"" (n pi)/(3) + isin"" (n pi)/(3), then z_(1), z_(2) …. Z_(6) is

If z_(r)=cos.(2rpi)/(5)+isin.(2rpi)/(5) , r=0,1,2,3,4 , then z_(1)z_(2)z_(3)z_(4)z_(5) equals

If Z_r =cos ((pi)/(2^r))+isin((pi)/(2^r)) then Z_(1).Z_(2).Z_(3)"…….." upto oo equals

If z_(1),z_(2),z_(3) are complex numbers such that : |z_(1)|=|z_(2)|=|z_(3)|=|(1)/(z_(1))+(1)/(z_(2))+(1)/(z_(3))|=1 , then |z_(1)+z_(2)+z_(3)| is equal to