If the orthocentre and the centroid of a triangle are $(-3,5,2)$ and $(3,3,4)$ respectively, then its…

If the orthocentre and the centroid of a triangle are $(-3,5,2)$ and $(3,3,4)$ respectively, then its circumcentre is
  1. $(6,2,5)$
  2. $(62,-5)$
  3. $(6,-2,5)$
  4. $(6,-2,-5)$

Solution

We know that, in a triangle, if $\mathrm{O}$ is orthocentre, $G$ is centroid and $S$ is circumcentre, then $\mathrm{SG}: \mathrm{G0}=1: 2$ Let circumcentre be $(x, y, z)$. $ \begin{array}{ll} \therefore & \left(\frac{-3+2 x}{1+2}, \frac{5+2 y}{1+2}, \frac{2+2 z}{1+2}\right)=(3,3,4) \\ \Rightarrow & \left(\frac{-3+2 x}{3}, \frac{5+2 y}{3}, \frac{2+2 z}{3}\right)=(3,3,4) \\ \Rightarrow & \frac{-3+2 x}{3}=3, \frac{5+2 y}{3}=3, \frac{2+2 z}{3}=4 \\ \Rightarrow & \quad x=6, y=2, z=5 \\ \therefore & S(6,2,5) . \end{array} $

Asked in: AP EAMCET 2018 (22 Apr Shift 1)

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