1.

If a_(1),a_(2),a_(3),...a_(n) are in A.P. with common difference d, then tan[tan^(-1)((d)/(1+a_(1)a_(2)))+tan^(-1)((d)/(1+a_(2)a_(3)))+,....+tan^(-1)((d)/(1+a_(n-1)a_(n)))]=

Answer»

`((N-1)d)/(a_(1)+a_(n))`
`((n-1)d)/(1+a_(1)a_(n))`
`(ND)/(1+a_(1)a_(n))`
`(a_(n)-a_(1))/(a_(n)+a_(1))`

ANSWER :B


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