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# how do I do this? watch

1. show that the circle (x-3)^2 + (y-5)^2 = 4 touches the circle x^2 + (y-1)^2 = 9

Is it simultaneous equations? what am I looking for? repeated root?
2. The distance between the centres = the sum of the radii.
3. (Original post by BabyMaths)
The distance between the centres = the sum of the radii.
so how would I go about doing that?
4. (Original post by madfish)
so how would I go about doing that?
Can you write down the centres and the radii?

Can you find the distance between two points?

Which bit can't you do?
5. (Original post by madfish)
show that the circle (x-3)^2 + (y-5)^2 = 4 touches the circle x^2 + (y-1)^2 = 9

Is it simultaneous equations? what am I looking for? repeated root?
Well show that the distance between the centres of the circle is equal to the sum of the radii...
6. (Original post by BabyMaths)
Can you write down the centres and the radii?

Can you find the distance between two points?

Which bit can't you do?
I can write down the centres and radii but what do I do next?
7. (Original post by madfish)
I can write down the centres and radii but what do I do next?
Find the distance between the centres.
8. (Original post by madfish)
I can write down the centres and radii but what do I do next?
distance between two points, and

9. (Original post by BabyMaths)
Find the distance between the centres.
okay so, circle1: r=2 centre = (3,5)

circle2: r=3 centre= (0,1)

I am sorry to sound dumb, but what do I do with this information?
10. Im guessing this is c2 because I forgotten it, what I would say is find the distance between the circle center of any of the circles to its circumference then find the distance between the center of the other cirlce to the circumferance of the opposite circle and it should be shorter than the distance in the first one. Because of the way circles are shaped it means they come into contact
11. (Original post by madfish)
okay so, circle1: r=2 centre = (3,5)

circle2: r=3 centre= (0,1)

I am sorry to sound dumb, but what do I do with this information?
Use the d formula above.

Add the radii.

What do you notice?
12. (Original post by madfish)
okay so, circle1: r=2 centre = (3,5)

circle2: r=3 centre= (0,1)

I am sorry to sound dumb, but what do I do with this information?
Do you know how to find the distance between the two centre points?

You've posted at least a couple of questions where you need this distance formula, so I would suggest grabbing a big sheet of A4 paper and writing down the distance formula on it (under a big heading saying DISTANCE FORMULA) and then you can refer to it when you need it
13. (Original post by davros)
Do you know how to find the distance between the two centre points?

You've posted at least a couple of questions where you need this distance formula, so I would suggest grabbing a big sheet of A4 paper and writing down the distance formula on it (under a big heading saying DISTANCE FORMULA) and then you can refer to it when you need it
PRSOM!

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