Question

Найти радиус сферы x^2+y^2-2y+z^2+6z-6=0

Answer 1

$x^2+y^2-2y+z^2+6z-6=0\\\\x^2+(y-1)^2-1+(z+3)^2-9-6=0\\\\x^2+(y-1)^2+(z+3)^2=16\\\\R^2=16\quad \Rightarrow \quad R=4\\\\Centr\; \; C(\, 0,1,-3)$