Question

If $(2,1,3),(3,2,5),(1,2,4)$ are the mid points of the sides $BC,CA,AB$ of $△ABC$ respectively, then vertex $A$ is:

• A. $(2,3,6)$
• B. $(0,2,2)$
• C. $(4,1,4)$
• D. $(2,5,4)$

Answer 1

The correct option is A $(2,3,6)$

$D=(2,1,3),E=(3,2,5),F=(1,2,4)$
$\Rightarrow A=E+F-D=(3+1-2,2+2-1,5+4-3)$
$\Rightarrow A=(2,3,6)$