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The vale of `sec(sin^-1(sin((-50pi)/9))+cos^-1(cos(31pi)/9))`A. `sec.(10pi)/(9)`B. `sec.(pi)/(9)`C. 1D. `-1`

Answer» Correct Answer - D
`sin^(-1)(-sin.(50pi)/(9))=sin^(-1)(sin(-6pi+(4pi)/(9)))`
`=sin^(-1)(sin.(4pi)/(9))`
`=(4pi)/(9)`
`cos^(-1)cos(-(31pi)/(9))=cos^(-1)cos((31pi)/(9))`
`=cos^(-1)cos(4pi-(5pi)/(9))=cos^(-1)cos.(5pi)/(9)=(5pi)/(9)`
Hence, given equals to sec `((4pi)/(9)+(5pi)/(9))=sec pi =-1`.


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