Question

Find the equation of circle, whose centre is $(3,4)$ and touches the axis of $y$.

Answer 1

Since the circle touches the y axis, the x-coordinate of its center will be the radius of the circle.

Thus its center is $(3,4)$ and the radius is $3$. So its equation is:

$(x-3{)}^2+(y-4{)}^2=9$

$\Rightarrow x^2+y^2-6x-8y+16=0$