If `costheta=(cosalpha-cosbeta)/(1-cosalpha.cosbeta)` , prove that `t a ntheta/2=+-tanalpha/2cotbeta/2` .

If costheta=(cosalpha+cosbeta)/(1+cosalphacosbeta),\ prove that tantheta/2=\ =-tanalpha/2tanbeta/2

If costheta=(cosalpha+cosbeta)/(1+cosalphacosbeta),\ prove that tantheta/2=+-tanalpha/2tanbeta/2

If costheta=(cosalpha-cosbeta)/(1-cosalphacosbeta) , then the values of tan(theta/2) is

(1+cosalphacosbeta)^2-(cosalpha+cosbeta)^2=

If costheta=(cosalpha cosbeta)/(1-sinalphasinbeta) , prove that one value of t a ntheta/2=(t a nalpha/2-t a nbeta/2)/(1-t a nalpha/2 t a nbeta/2)

If costheta=(cosalpha-e)/(1-e cosalpha),\ prove that tantheta/2=+-sqrt((1+e)/(1-e))tanalpha/2dot

If costheta=(cosalpha-cosbeta)/(1-cosalphacosbeta) . prove that one of the value of "tan"(theta)/(2) is "tan"(alpha)/(2)"cot"(beta)/(2) .

(cosalpha+cosbeta)^2+(sinalpha+sinbeta)^2 =

Prove that : cos^(-1)((cosalpha+cosbeta)/(1+cosalphacosbeta))=2\ tan^(-1)(tanalpha/2tanbeta/2)

Prove that |cosalpha-cosbeta|lt=|alpha-beta|