1.

Prove that `(d)/(dx)(sin^(-1)x)=(1)/(sqrt(1-x^(2))`, where `x in [-1,1].`

Answer» Let `y=sin^(-1)x`, where `x in [-1,1] and y- in [-(pi)/(2),(pi)/(2)].` Then,
`y=sin^(-1)x rArr x= sin y`
`rArr(dx)/(dy)=cosy ge0" since "yin[-(pi)/(2),(pi)/(2)]`
`rArr(dx)/(dy)=sqrt(1-sin^(2)y)=sqrt(1-x^(2))`
`rArr(dy)/(dx)=(1)/(sqrt(1-x^(2)))`
Hence, `(d)/(dx)(sin^(-1)x)=(1)/(sqrt(1-x^(2))).`


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