Question

Find the equation of the circle which touches the both axes in first quadrant and whose radius is $a$?

Answer 1

Given that the circle touches both the $x$ and $y$ axes in the first quadrant and the radius is $a$.

For a circle of radius a, the centre is $(a,a)$.

Therefore, the equation of the circle becomes $(x–a{)}^2+(y–a{)}^2=a^2$