# Thread: Equation of a Circle

1. ## Equation of a Circle

Well the knowledge of it I just simply forgot about and don't remember a single thing about how to do it.

Write the equation of a circle with center (4,0) and passing through the point (12,6).

I don't want just an answer, I need the method of how to do it. Also I might also need help understanding this question as well

Write the equation of a circle with center (6,6) and tangent in both axes.

THANKS!!!

2. Originally Posted by MagicBirdy
Well the knowledge of it I just simply forgot about and don't remember a single thing about how to do it.

Write the equation of a circle with center (4,0) and passing through the point (12,6).

I don't want just an answer, I need the method of how to do it. Also I might also need help understanding this question as well

Write the equation of a circle with center (6,6) and tangent in both axes.

THANKS!!!
the equation of a circle is given by: $(x - h)^2 + (y - k)^2 = r^2$

where $(h,k)$ is the center and $r$ is the radius

so fill in what you know for your circle.

you are also given the additional information that when $x = 12$, $y = 6$, you can use this to solve for $r$

for the second question, you know that the circle passes through (0,6) and (6,0) ........which tells you the radius is 6