Question

write an equation of the circle that is tangent to both axes with radius sqrt5 and center in quadrant 3

Answer 1

Check the picture below.

$\bf \textit{equation of a circle}\\\\ (x-{{ h}})^2+(y-{{ k}})^2={{ r}}^2 ~~ \begin{array}{lllll} center~(&\quad {{ h}},&\quad {{ k}}\quad )\qquad radius=&{{ r}}\\ &-\sqrt{5}&-\sqrt{5}&\sqrt{5} \end{array} \\\\\\\ [x-(-\sqrt{5})]^2+[y-(-\sqrt{5})]^2=(\sqrt{5})^2 \\\\\\ (x+\sqrt{5})^2+(y+\sqrt{5})^2=5$