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

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

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

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

4costheta cos 2theta cos3theta - 2cos 4theta=1

cos theta cos2 theta cos3 theta=(1)/(4)

cos 4theta = cos 3theta - cos2theta

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

costheta-cos2theta=sin3theta

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