1.

If `tan^-1x, tan^-1y` and `tan^-1z` are in A.P. then find the algebraic relation between x,y and z. If `x,y,z` are also in A.P. then show that `x=y=z` and `y!=0`A. `x=y=zory!=1`B. `x=1//z`C. x=y=z, but their common value is not necessarily zeroD. x=y=z=0

Answer» Correct Answer - C
`:." "y^(2)=xz` . . .(i)
Also,
`tan^(-1)x,tan^(-1)y,tan^(-1)z` are in A.P.
`:." "2tan^(-1)y,tan^(-1)x,tan^(-1)z`
`rArr" "tan^(-1)((2y)/(a-y^(2)))=tan^(-1)((x+z)/(1-xz))`
`rArr" "(2y)/(1-y^(2))=(x+z)/(1-xz)`
`rArr" "(2y)/(1-xz)=(x+z)/(1-xz)" [Using (i)]"`
`rArr" "` x,y,z are in A.P. . . . (ii)
From (i) and (ii), we get
x=y=z


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