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

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

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

Find the sum: costheta+ (a cos2theta)/(1!)+(a^2cos3theta)/(2!)+(a^3cos4theta)/(3!)+…to oo

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

int(costheta-cos2theta)/(1-cos theta)d theta=

costheta.cos2theta.cos3theta=1/4

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

costheta-cos2theta=sin3theta

Solve: cos3theta+2costheta=0