# Tangent to y axis with center(-3,4) whats the eqn of circle?

1. Mar 26, 2005

### aisha

the center is (-3,4) and tangent to the y-axis

how will I find the equation of the circle?

I know what tangent means but at what point? Can someone give me a clue?

2. Mar 27, 2005

### Math Is Hard

Staff Emeritus
I am pretty rusty at this, and I am not sure I understand the wording, but could it simply mean that your circle touches the point (0,4) on the y-axis? I am assuming that the line x = 0 is tangent to the curve.

3. Mar 27, 2005

### aisha

I think the radius is 3

therefore the equation of the circle is

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

is this correct?

4. Mar 27, 2005

### Data

that's fine~

5. Mar 27, 2005

### aisha

how come the radius wasnt 4?

6. Mar 27, 2005

### Data

the center is at $(-3, 4)$ and the circle is tangent to the $y$ axis, which implies that it is tangent at $(0, 4)$. Thus the radius is the distance between $(0, 4)$ and $(-3, 4)$ which is clearly 3.