# Thread: circle equation

1. ## circle equation

I'm just drawing a blank under pressue.

I only have an hour.

Find the standard form of the equation for the circle described below:

Radius: 2sqrt(2) and center (5,-8)

Thanks

2. Originally Posted by mankvill
I'm just drawing a blank under pressue.

I only have an hour.

Find the standard form of the equation for the circle described below:

Radius: 2sqrt(2) and center (5,-8)

Thanks
The equation of a circle with center M(h, k) and radius r is:

$(x-h)^2+(y-k)^2=r^2$

Plug in the values you know and then you can transform this equation as you like it.

3. Here's another that I know how to do, I'm just blanking.

Parallel line to:

y = x - 5/3

4. Originally Posted by earboth
The equation of a circle with center M(h, k) and radius r is:

$(x-h)^2+(y-k)^2=r^2$

Plug in the values you know and then you can transform this equation as you like it.
I got $(x-5)^2+(y+8)^2=8$

Is that right?

5. UGH, here's another one. I'm terrible with interval notation:

Domain And Range in interval notation:

$-2y-5x=-3$

6. Originally Posted by mankvill
Here's another that I know how to do, I'm just blanking.

Parallel line to:

y = x - 5/3
First I would like to know if I could help you with my previous post.
Second: Do us and do yourself a favour and start a new thread if you have a new problem to solve.

Third: A parallel line to

$y = 1 \cdot x- \frac53$ must have the same slope, here in this case the slope is m = 1.

Therefore a parallel line has the equation:

$y = x + c$

7. Originally Posted by mankvill
I got $(x-5)^2+(y+8)^2=8$

Is that right?
Precisely!

8. Originally Posted by mankvill
UGH, here's another one. I'm terrible with interval notation:

Domain And Range in interval notation:

$-2y-5x=-3$
Are you sure that this is the exact text of your problem? The given equation describes a straight line with $D=\mathbb{R}$ and $R=\mathbb{R}$

9. Thank you very much, and I will start new threads from now on.

10. Originally Posted by mankvill
UGH, here's another one. I'm terrible with interval notation:

Domain And Range in interval notation:

$-2y-5x=-3$

$D = (-\infty, +\infty)$

$R = (-\infty, +\infty)$