# How do you find the center and radius for X^2 + Y^2 = 13?

Jan 7, 2016

centre = (0 , 0 ) and r = $\sqrt{13}$

#### Explanation:

require to compare this equation with the standard form of the equation of a circle.

${\left(x - a\right)}^{2} + {\left(y - b\right)}^{2} = {r}^{2}$

where (a , b ) represents the centre of the circle and r the radius

${X}^{2} + {Y}^{2} = {\left(X - 0\right)}^{2} + {\left(Y - 0\right)}^{2}$

${r}^{2} = 13 \Rightarrow r = \sqrt{13}$

hence centre = (0 ,0 ) and radius = $\sqrt{13}$