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Grade 12th passTrigonometry

If, tanA+sinA=m, tanA-sinA=n. Then prove that, tanA.sinA=√mn

Profile image of Mahmudul Hasan
7 Years agoGrade 12th pass
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1 Answer

Profile image of Samyak Jain
7 Years ago
tanA + sinA = m     …..(1)   &   tanA – sinA = n      ….(2)
Simply multiply (1) & (2).
(tanA + sinA)(tanA – sinA) = mn
tan2A – sin2A = mn  \Rightarrow  sin2A / cos2A – sin2A = mn
sin2A (1 – cos2A)/cos2A  =  mn
i.e. (sin2A/cos2A)(sin2A) = mn          [1 – sin2A = cos2A]
tan2A . sin2A = \sqrt{mn}