## anonymous 3 years ago Find the center and radius of a circle that has a diameter with endpoints (-9, -6) and (-1,0). Show work. a) center (4,3); radius 5 b) center (8,6); radius 10 c) center (-5,-3); radius 5 d) center (-10,-6); radius 10

1. anonymous

Center would be the midpoint between those two points, and the radius would be the distance between them divided by 2

2. anonymous

So I do the midpoint formula using the two points to find the center?

3. Hero

Graph paper would work great for this problem

4. anonymous

Yep, use the midpoint formula

5. anonymous

What do you get?

6. anonymous

(-5,-3)

7. anonymous

8. anonymous

I know its suppose to be 5, but I didn't get it.

9. anonymous

Do you know the distance formula?

10. anonymous

Wait, I think I know why..

11. anonymous

I still didn't get it. Isn't it d=$\sqrt{(x2-x1)^{2}+(y2-y1)^{2}}$

12. anonymous

Yeah thats it. Plug in your coordinates $D=\sqrt{(-1+9)^2+(0+6)^2}$

13. anonymous

youll get d=sqrt{100} d=10 but remember thats the diameter, radius is diameter divided by 2. 10/2=5

14. anonymous

Oh, I got it now. I just added wrong. Thanks!

15. anonymous

You're welcome

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