If Tan−1x+Tan−1y+tan−1z=π2then
xy+yz+zx=1
x2+y2+z2+2xyz=1
x+y+z=xyz
None
Let tan-1x=A, tan-1y=B, tan-1z=C. ⇒tanA=x, tanB=y, tanC=z. Given tan-1x+tan-1y+tan-1z=π2. ⇒A+B+C=π2 ⇒tanAtanB+tanBtanC+tanCtanA=1 ⇒xy+yz+zx=1