`(sin(3pi/7) cos(4pi/7))/sin(pi/7)`

Prove that: sin((4pi)/9+7)cos(pi/9+7)-cos((4pi)/9+7)sin("pi/9+7)=(sqrt(3))/2

the value of sin(pi/7)+sin((2pi)/7)+sin((3pi)/7) is

If A=sin((2pi)/7)+sin((4pi)/7)+sin((8pi)/7) and B=cos((2pi)/7)+cos((4pi)/7)+cos((8pi)/7) then sqrt(A^2+B^2) is equal to

The value of cos(pi/7)+cos((2pi)/7)+cos((3pi)/7)+cos((4pi)/7)+cos((5pi)/7) +cos((6pi)/7)+cos((7pi)/7) is

cos(pi/7)+cos((2pi)/7)+cos((3pi)/7)+cos((4pi)/7)+cos((5pi)/7)+cos((6pi)/7)=

The value of cos(pi/7)+cos((2pi)/7)+cos((3pi)/7)+cos((4pi)/7)+cos((5pi)/7)+cos((6pi)/7)+cos((7pi)/7) is 1 (b) -1 (c) 0 (d) none of these

The value of cos(pi/7)+cos((2pi)/7)+cos((3pi)/7)+cos((4pi)/7)+cos((5pi)/7)+cos((6pi)/7)+cos((7pi)/7) is 1 (b) -1 (c) 0 (d) none of these

How to evalvate (sin (3 pi)) / (7) (cos (4 pi)) / (7)) / (sin pi) / (7)) = (- 1) / (2)

sin((7pi)/(12))cos(pi/4)-cos((7pi)/(12))sin(pi/4)=...........