Prove that : (1-sinA)/(1+sinA) = tan2(45-(A/2))

Dear STudent, 
It can be written as
tan45-A2=1-sinA1+sinANow LHStan45-A2=tan45-tanA21+tan45×tanA2=1-sinA2cosA21+sinA2cosA2=cosA2-sinA2cosA2+sinA2=cosA2-sinA2cosA2+sinA2×cosA2-sinA2cosA2-sinA2=cosA2-sinA22cos2A2-sin2A2=cos2A2+sin2A2-2cosA2sinA2cosA=1-sinAcosA= 1-sinA1-sin2A=1-sinA21-sinA1+sinA=1-sinA1+sinA= RHSRegards

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