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

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

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+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)+…

Solve cos theta+cos 2theta+cos 3theta=0 .

Solve: cos3theta+2costheta=0

Solve: cos3theta+costheta=0

If tan theta=sqrt(3/2) and the sum of the infinite series 1+2(1-cos theta)+3(1-cos theta)^2+4(1-cos theta)^3+.........+oo is lambda/2 then the value of lambda is (1) 2 (2) 5 (3) 1 (4) 4