Question

Find the coordinates for the center and length of radius for this circle.

(x + 3)2 + (y - 5)2 = 25

center (,)

radius

Answer 1

What is the equation for a circle?

Answer 2

(x-h squared) + (y-k squared) = r squared

Answer 3

right. How can you make a plus out of minuses (Hint: x+3 needs to look like x - something)

Answer 4

x - 6

Answer 5

no i have to square 3 so it should be 9

Answer 6

Remember that you need the 3 in there somewhere. x+3 is the same as x - (-3) isn't it?

Answer 7

thats correct

Answer 8

DO NOT EXPAND!!!! The answer is in front of you.

Answer 9

is it 9 and 25 and radius 5

Answer 10

the center is 9 and 25
radius 5

Answer 11

The radius is 5...But you have to find h and k to find the center. That means that you need to make (x+3) look like (x - (-3)). What's h?

Then, look at (y-5). Does is look like (y-k)? If so, what's k?

Answer 12

The center is at (h, k)

Answer 13

-3

Answer 14

what's k?

Answer 15

-5

Answer 16

Look at the structure:\[(x-h)^{2} +(y-k)^{2}=r^{2}\]

Answer 17

The minus sign MUST be there. What's k?

Answer 18

-5

Answer 19

so basically its the same numbers but you have to make them negative

Answer 20

Sorry. Just 5. No negative. We needed a negative on the 3 for x because there was a plus sign in between, and we needed a minus sign.

Answer 21

Center at (h, k) = (-3, 5)

Answer 22

When working with these types of equations, the structure (signs, powers, placement) is the important thing.

Answer 23

okay can you help with the next one to see if i understand

Answer 24

Find the coordinates for the center and length of radius for this circle.

(x - 3)2 + (y - 5)2 = 8

center (,)

radius

Answer 25

so the answer would be 3, 5 and 2 square root of 2

Answer 26

right

Answer 27

i am not sure about 2 square root of 2 because it should equally 8

Answer 28

okay thanks

Answer 29

this is alot easier than i thought it would be

Answer 30

But remember that the radius is the square root of what's on the right. Simplifying that is what gave you the 2root 2

Answer 31

Yeah, it's not bad.

Answer 32

Find the coordinates for the center and length of radius for this circle.

(x - 4)2 + y2 = 12 on this one what do i do with the y squared would it be -1

Answer 33

There is no k, so k=0