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# C2 Chapter 4 help!! watch

1. A Circle C1 has equation x^2+y^2-12x+4y+20=0
A) find coordinates of the centre of C1
B) find the radius of C1

The circle C1 cuts the x-axis at the points A and B
C) find an equation of the circle C2 with diameter AB

2. (Original post by xALMOSTxPERFECTx)
A Circle C1 has equation x^2+y^2-12x+4y+20=0
A) find coordinates of the centre of C1
B) find the radius of C1

The circle C1 cuts the x-axis at the points A and B
C) find an equation of the circle C2 with diameter AB

What is the centre of a circle with equation (x-a)^2 + (y-b)^2 = r^2?
3. (Original post by SeanFM)
What is the centre of a circle with equation (x-a)^2 + (y-b)^2 = r^2?
Umm I don't know?? :/
4. (Original post by xALMOSTxPERFECTx)
Umm I don't know?? :/
5. (Original post by RDKGames)
I don't have any that's the problem, hence why I've asked for help
6. (Original post by xALMOSTxPERFECTx)
I don't have any that's the problem, hence why I've asked for help
Have you covered this topic then?
7. (Original post by xALMOSTxPERFECTx)
Umm I don't know?? :/
Check your textbook, I think it would be best to revise the content first before coming back to the questikn
8. (Original post by RDKGames)
Have you covered this topic then?
No I haven't. Teacher gave it to us to try it out, I have no idea what I'm doing. The textbook isn't helping me because it hasn't got any of the same questions in it
9. (Original post by xALMOSTxPERFECTx)
No I haven't. Teacher gave it to us to try it out, I have no idea what I'm doing. The textbook isn't helping me because it hasn't got any of the same questions in it
You should look at the content first.

A circle in the form has radius with centre coordinates

To complete the first question you need to complete the square on and and get the equation into the general form before determining the centre and radius. Look at the content for more information.
10. (Original post by RDKGames)
You should look at the content first.

A circle in the form has radius with centre coordinates

To complete the first question you need to complete the square on and and get the equation into the general form before determining the centre and radius. Look at the content for more information.
Thank you, I'll try that but I still think I'm confused

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Updated: February 8, 2017
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