[" If "alpha=(pi)/(18)" radians,then "],[cos alpha+cos2 alpha+....+cos18 alpha=]

Statement-I If alpha=(pi)/(18) then cos alpha+ cos 2 alpha+..... +cos18 alpha=0 Statement- II If (a+2) sin theta(2a-1) cos theta=2a+1 then tan theta=(4)/(3) Which of the above statements is correct

If alpha =(pi)/(18) radian then the value of (cos alpha + cos 2 alpha+ cos 3 alpha +…+ cos 18 alpha) is-

If alpha= (2pi)/(7) , then prove that cos alpha+ cos 2 alpha+ cos 4alpha=-(1)/(2) . Hence, deduce that sin alpha+ sin 2alpha+ sin 4alpha=(sqrt(7))/(2)

If alpha = (pi)/(13), Prove that cos alpha cos 2alpha cos 3alpha cos 4alpha cos 5alpha cos 6alpha = (1)/(64) .

If alpha=(pi)/(17), show that (cos alpha cos13 alpha)/(cos3 alpha+cos5 alpha)=-(1)/(2)

If alpha=(pi)/(23) then the value of (cos10 alpha-cos22 alpha)/(cos10 alpha-cos24 alpha) is equal to

(cos2 x - cos2 alpha)/(cos x - cos alpha)

If alpha-beta=(2n+1)(pi)/2, n epsilon Z then [(cos^(2) alpha, cos alpha sin alpha),(cos alpha sin alpha, sin^(2)alpha)][(cos^(2) beta, cos beta sin beta),(cos beta sin beta, sin^(2) beta)]=

If alpha=(pi)/(7) then find the value of ((1)/(cos alpha)+(2cos alpha)/(cos2 alpha))

If pi