Find the sum of the series: `1+xcostheta+x^2cos2theta+…to oo`

Find the sum of the series 1+cos^2theta+cos^2thetacos2theta+cos^3 theta cos3theta+… to oo

Find the sum of the series costheta- (cos2theta)/(2!)+(cos3theta)/(3!)-… to oo

Find the sum of the series costheta.cos2theta+cos3theta.cos4theta+cos5theta.cos6theta+…to n terms

Find the sum of the series cos e ctheta+cos e c2theta+cos e c4theta+ tont e r m sdot

Find the sum of n terms the series: 1/(costheta+cos3theta)+1/(costheta+cos5theta)+1/(costheta+cos7theta)+…

Find the sum to n terms of the series cottheta.cot 2theta+cot2theta.cot3theta+…

Find the sum of the series sintheta- (sin2theta)/(2!)+(sin3theta)/(3!)-… to oo

Find the sum of series cosec theta+cosec 2 theta+cosec 4 theta+....... to n terms .

Find the sum of the series cosalpha+x cos(alpha+beta)+ x^2/(2!)cos(alpha+2beta)+…to oo

Find the sum sintheta+x sin 2theta+x^2sin 3theta+… to oo