The coordinates of the foot of the perpendicular drawn from the origin to the plane $2 x+y-2 z=18$ are

The coordinates of the foot of the perpendicular drawn from the origin to the plane $2 x+y-2 z=18$ are
  1. $(4,2,-4)$
  2. $(1,2,-3)$
  3. $(4,2,4)$
  4. $(4,-2,-4)$

Solution

$2 x+y-2 z=18$ Dividing both sides $\sqrt{(2)^2+(1)^2+(-2)^2}=3$, we get $\left(\frac{2}{3}\right) \mathrm{x}+\left(\frac{1}{3}\right) \mathrm{y}-\left(\frac{2}{3}\right) \mathrm{z}=6$ Hence length of perpendicular from origin to the plane is 6 . Therefore coordinates of foot of perpendicular are $\left[\left(\frac{2}{3}\right)(6),\left(\frac{1}{3}\right)(6),\left(\frac{-2}{3}\right)(6)\right]$ i.e. $(4,2,-4)$

Asked in: MHT CET 2021 (23 Sep Shift 2)

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