#64cos^3thetasin^4theta#
= #8cos^3thetasin^3theta*8sintheta#
= #(sin2theta)^3*8sintheta#
= #2*2sin2thetasintheta*2sin^2 2theta#
= #2*(cos(2theta-theta)-cos(2theta+theta))*(1-cos4theta)#
= #2*(costheta-cos3theta)*(1-cos4theta)#
= #2costheta-2cos3theta-2costhetacos4theta+2cos4thetacos3theta#
= #2costheta-2cos3theta-(cos5theta+cos3theta)+(cos7theta+costheta)#
= #cos7theta-cos5theta-3cos3theta+3costheta#