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Home > Inverse Trigonometric Functions
Prove the following:
tan-1 x = 12 cos-1 1 - x1 + x , x∈ 0, 1
Let t = tan-1 xSo x = tan ti.e. tan2 t = xOn substituting x in the R.H.S. of equation tan-1 x = 12 cos-1 1 - x1 + x ,We get 12 cos-1 1 - x1 + x = 12 cos-1 1 - tan2 t1 + tan2 t Now, using the formula cos 2θ = 1 - tan2 θ1 + tan2 θ we have 12 cos-1 1 - x1 + x =12 cos-1 cos 2t = t = tan-1 x = L.H.S.
Hence proved.
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