# Math Help - Sphere

1. ## Sphere

Find equation of largest sphere with center $(5,4,9)$.

Would it have $r = 4$ because if $r = 5$ or $r = 9$ the sphere would lie outside first octant?

2. Hello, shilz222!

Find equation of largest sphere with center $(5,4,9)$
As stated, there is no "largest sphere".

From your follow-up statement, I assume that the sphere must be in the first octant.

If that's true, you are correct: the maximum radius would be 4.

. . The equation would be: . $(x-5)^2 + (y-4)^2 + (z-9)^2 \;=\;16$