A points P(1,2,3) is one vertex of a cuboid formed by the coordinate planes and the planes passing through P and parallel to the coordinate planes.
The radius of the sphere
`3x^2+3y^2+3z^2-8x+4y+8z-15=0` is

Options

A. 2
B. 3
C. 4
D. 5

Answer

B

Explanation

(b) `3x^2+3y^2+3z^2-8y+4y+8z-15=0`
`rArr x^3+y^2+z^2-8/3x+4/3y+8/3z-5=0`
`rArr(x-4/3)^2-16/9+(y+2/3)^2-4/9+(z+4/3)^2-16/9-5=0`
`rArr (x-4/3)^2+(y+2/3)^2+(z+4/3)^2=(3)^2`
So radius is 3.