`cosfrac{pi}{7}+cosfrac{2pi}{7}+cosfrac{3pi}{7}+cosfrac{4pi}{7}+cosfrac{5pi}{7}+cosfrac{6pi}{7}=`
1) 0
2) 1
3) -1
4) 2

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

cos(pi/7) cos((3pi)/7) cos((5pi)/7) is (A) 1/8 (B) -1/8 (C) 1/(2sqrt2) (D) 1/2

Find the value of cospi/7+cos(2pi)/7+cos(3pi)/7+cos(4pi)/7+cos(5pi)/7+cos(6pi)/+cos(7pi)/7

Prove that cos ((2pi)/7)+ cos ((4pi)/7) + cos ((6pi)/7) = - 1/2

Prove that: cos(pi/7)cos(2pi/7)cos(4pi/7)=-1/8,

If P = [[cos frac(pi)(6), sin frac(pi)(6) ],[-sinfrac(pi)(6),cosfrac(pi)(6)]], A = [[1,1],[0,1]] then P+ A

Statement-1 : "cos"pi/7+"cos"(2pi)/7+"cos"(3pi)/7+"cos"(4pi)/7+"cos"(5pi)/7+"cos"(6pi)/7 vanishes Statement-2 : Sum of the cosines of two supplementary angles vanishes.

Prove that : cos(pi/7)cos((2pi)/7) cos((3pi)/7)=1/8

Prove that 4cos((2pi)/7).cos(pi/7)-1=2cos((2pi)/7) .

Prove that: cos(pi/7)cos((2pi)/7)cos((4pi)/7)=-1/8