Question

Find centre and radius of the following circles

x² + (y + 2)² = 0

Answer 1

x² + (y + 2)² = 0

(i.e) x² + y² + 4y + 4 = 0

Comparing this equation with the general form x² + y² + 2gx + 2fy + c = 0

We get 2g = 0

⇒ g = 0

2f = 4

⇒ f = 2 and c = 4

Now centre = (– g, – f) = (0, – 2)

Radius = r 

= `sqrt(g^2 + f^2 - "c")`

= `sqrt(0 + 4 - 4)`

∴ Centre = (0, – 2) and radius = 0