Question

if costheta=cosA-cosB/1-cosA.cosB prove that one of the values of tantheta/2 is tanA/2.cotB/2
plzz solve it ​

Answer 1

Answer:

i think first use the formula cos(θ/2)= sqrt[(1+cos θ)/2]

and then covert it into sec(θ/2) and use

sec(θ/2)^2 - 1 = tan(θ/2)^2

but i have reached till

tan(θ/2) =

sqrt [(1+cosAcosB-cosA+cosB) / (1-cosAcosB+cosA-cosB)]

if only i could simplify. u can try by using cosA=2cos(a/2)^2 - 1

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