# What is the general form of the equation of a circle with a center at the origin and a radius of 9?

##### 2 Answers

Dec 26, 2015

#### Explanation:

Any general circle centred at

So in this case since the centre is the origin, it implies that

Thus the equation reduces to

Dec 26, 2015

#### Explanation:

General Equation of a circle:

where (a,b) are the coordinates of center and 'r' is the radius

since in you question center lies on origin and the radius is 9

therefore, (a,b) = (0,0) and r=9

hence,