sum_(r=1)^(9)sin^(2)(r pi)/(18)=

If sum_(r=15)^(29)cos((r pi)/(2)+theta)=S_(1) and sum_(r=15)^(29)sin((r pi)/(2)+theta)=S_(2) then find the value of (s_(2))/(s_(1))

let a=sum_(r=1)^(6)cos((r pi)/(7)),b=sum_(r=1)^(6)cos^(2)((r pi)/(7)),c=sum_(1<=i)sum_(j<=6)cos((i pi)/(7))cos((j pi)/(7)) then find the value of (a-b)/(c)

Prove that sum_(r=1)^(10) = sin^(2) rpi/18 =5 .

The value of sum_(r=1)^(11)tan^(2)((r pi)/(24)) is

The value of sum_(r=1)^(11)tan^(2)((r pi)/(24)) is

If sum_(r=15)^(29)(cos(r(pi)/(2)+theta)=S_(1) and sum_(r=15)^(29)(sin(r(pi)/(2)+theta)=S_(2), then (S_(1))/(S_(2)) equals

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