Analytic Geometry(CIRCLES): Find the center/radius of the circle x^2+y^2-6+1=0.

Question

How do you get the radius if there's only one Y that is given?

Answer 1

x^2+y^2-6+1 = 0

Subtract 1 from each side.

x^2+y^2-6+1-1 = 0-1

x^2+y^2-6 = -1

Add 6 to each side.

x^2+y^2 -6+6 = -1+6

x^2+y^2 = 5

Compare it to standerd form of a circle x^2+y^2 = r^2.

Here r ^2 = 5  and center is origin (0,0).

radius = sqrt(5)