# How do you find the center and the radius of the circle whose equation is #x^2+y^2-4x-2y-4=0#?

##### 1 Answer

Jan 11, 2016

centre = (2 , 1 ) and radius = 3

#### Explanation:

comparing the general form for the equation of a circle :

with the question given

# x^2 + y^2- 4x -2y - 4 = 0

comparing terms we can see that 2g = - 4 hence g = - 2

similarly 2f = - 2 hence f = - 1 and c = - 4

the centre of the circle = (- g , - f ) = (2 , 1 ) and

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