`sum_(r=1)^(2002+(2k-1))cos((2rpi)/7)+isin((2rpi)/7)=0` then the non negative integtral values of k less than 10 may be

sum_(r=1)^(n-1)cos^(2)""(rpi)/(n) is equal to

sum_(r =1)^(16) ( sin [(2r pi)/(17)] + icos [(2rpi)/(17)] ) =

Find sum_(r=1)^(10) cos^(3) rpi/3 .

The value of sum_(r=1)^(8)(sin((2rpi)/9)+icos((2rpi)/9)) , is

Evaluate sum_(r=1)^(n-1) cos^(2) ((rpi)/(n)) .

Evaluate sum_(r=1)^(n-1) cos^(2) ((rpi)/(n)) .

If [(cos\ (2pi)/7,-sin\ (2pi)/7),(sin\ (2pi)/7,cos\ (2pi)/7)]^k=[(1,0),(0,1)], then the least positive integral value of k , is

If [(cos (2pi)/7,-sin (2pi)/7),(sin (2pi)/7,cos (2pi)/7)]^k=[(1,0),(0,1)], then the least positive integral value of k, is