Standard form equations of circles

[Guest]

standard form of the equationg of a circle is:
(x-h)^2 +(y-k)^2 = r^2
The center of a circle is (h, k)

I have 4 different problems pertaining to this. The first 2, I attempted, and the second 2 I didn't know how to do.

1) Center: (0, 0); radius: 5
For the answer, I came up with : x^2+y^2=25

2) Center: (0, 1/3); radius: 1/3
And this is how I figured it out: (x-0)^2 + (y- 1/3)^2 =(1/3)^2
= x^2 + (y- 1/3)^2 = 1/9

3)Center: (3, -2) ; Solution point= (-1, 1)


4) Endpoints of a diameter: (-4, -1) , (4, 1)


Please help if you can !

 

[skeeter]

standard form of the equationg of a circle is:
(x-h)^2 +(y-k)^2 = r^2
The center of a circle is (h, k)

I have 4 different problems pertaining to this. The first 2, I attempted, and the second 2 I didn't know how to do.

1) Center: (0, 0); radius: 5
For the answer, I came up with : x^2+y^2=25

2) Center: (0, 1/3); radius: 1/3
And this is how I figured it out: (x-0)^2 + (y- 1/3)^2 =(1/3)^2
= x^2 + (y- 1/3)^2 = 1/9

3)Center: (3, -2) ; Solution point= (-1, 1)

the distance between the center and the solution point is the radius ... remember the distance formula?



4) Endpoints of a diameter: (-4, -1) , (4, 1)

center is the midpoint of the diameter endpoints ... diameter distance = 2 times the radius.


Please help if you can !

 

[Guest]

hmm.. I still don't understand how to do them.. How would you set them up?

 

[tkhunny]

Answer the questions.

Do you know how to calculate the distance between two points?
Do you know how the Diameer relates to the Radius?