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# Finding the equation of a circle watch

1. Given that (9,5) is the diameter of Circle C, find the equation for C:

I thought it might be x2 + y2 = 10.32... I do not think this is correct.

Please can you go through it for me?
Thank you.
2. (Original post by RosaA)
Given that (9,5) is the diameter of Circle C, find the equation for C:

I thought it might be x2 + y2 = 10.32... I do not think this is correct.

Please can you go through it for me?
Thank you.
what do you mean by "(9,5) is the diameter"?

is it possible for you to post a photo/link to the question?
3. (Original post by RosaA)
Given that (9,5) is the diameter of Circle C, find the equation for C:

I thought it might be x2 + y2 = 10.32... I do not think this is correct.

Please can you go through it for me?
Thank you.
The question doesn't make sense as it stands. (9,5) is a point, not a scalar quantity for a diameter.
4. Do you mean (9,5) is the center?
5. (Original post by RDKGames)
The question doesn't make sense as it stands. (9,5) is a point, not a scalar quantity for a diameter.
That is what I was getting confused about! It didn't make much sense to me either...
6. The question
Attached Images

7. lets see the question.
8. (Original post by RosaA)
Given that (9,5) is the diameter of Circle C, find the equation for C:

I thought it might be x2 + y2 = 10.32... I do not think this is correct.

Please can you go through it for me?
Thank you.
Can you post the original question?

A circle with centre (a,b) and radius r has the equation:

You gave one piece of information, , but, even if that were a vector for the diameter, we'd still need the centre. If it's the centre, we still need the radius.
9. (Original post by RosaA)
The question
Yeah so that question makes sense.

Since AB is the diameter - the midpoint between A and B is the centre, and half the distance between A and B is the radius. Enough info to define a circle.
10. I see that you've posted the question - you find the centre of the circle in (a) and can calculate the radius from , or using or .

is the centre, so you're right so far.

What is ? What does that distance represent?

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