If tan-1x+tan-1y+tan-1z=π, then x+y+z=
(1)
Ans. xyz
Explanation:
Given,
tan-1x+tan-1y+tan-1z=π
⇒ tan-1x+tan-1y=π-tan-1z
⇒ tan-1(x+y1-xy)=π-tan-1z
⇒ x+y1-xy=tan(π-tan-1z)
⇒ x+y1-xy=-tan(tan-1z)=-z
⇒ x+y=-z+xyz
⇒ x+y+z=xyz