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Prove that `sin^(-1)(8/(17))+sin^(-1)(3/5)=cos^(-1)((36)/(85))`

Answer» Here, we will use,
`sin^-1x+sin^-1y = sin^-1(xsqrt(1-y^2)+ysqrt(1-x^2))`
`L.H.S. = sin^-1(8/17)+sin^-1(3/5)`
`=sin^-1(8/17sqrt(1-(3/5)^2)+3/5sqrt(1-(8/17)^2))`
`=sin^-1(8/17(4/5)+3/5(15/17))`
`=sin^-1(32/85+45/85)`
`=sin^-1(77/85)`
`=cos^-1(sqrt(1-(77/85)^2))`
`=cos^-1(sqrt(1296/7225))`
`=cos^-1(36/85) = R.H.S.`


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