If $O A$ is equally inclined to $O X, O Y$ and $O Z$ and if $A$ is $\sqrt{3}$ units from the origin, then…

If $O A$ is equally inclined to $O X, O Y$ and $O Z$ and if $A$ is $\sqrt{3}$ units from the origin, then $A$ is :
  1. $(3,3,3)$
  2. $(-1,1,-1)$
  3. $(-1,1,1)$
  4. $(1,1,1)$

Solution

Since $O A$ is equally inclined to $O X, O Y$ and $O Z$. $\therefore$ Co-ordinates of $A$ are $(a, a, a)$. Also $O A=\sqrt{3}$ $\therefore \quad \sqrt{(a-0)^2+(a-0)^2+(a-0)^2}=\sqrt{3}$ $\Rightarrow \quad \sqrt{3 a^2}=\sqrt{3}$ $\Rightarrow \quad a^2=1$ $\Rightarrow \quad a= \pm 1$ $\therefore$ Co-ordinates of $A$ are $(1,1,1)$ or $(-1,-1,-1)$.

Asked in: AP EAMCET 2006

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