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# Circle Geometry Question watch

1. Q: a circle passes through the points (0,-3) and (0,3) and has radius 5. Draw a sketch to show the two possible positions of the circles and find their equations.

Help would really be appreciated.

This is what I have done so far:
2. (Original post by TarotOfMagic)
Q: a circle passes through the points (0,-3) and (0,3) and has radius 5. Draw a sketch to show the two possible positions of the circles and find their equations.

Help would really be appreciated.

This is what I have done so far:

Ah, do you see what's wrong with your circle?

Look at the radius. It's 3, but the radius stated is 5.
So this circle cannot be correct.
Spoiler:
Show
Hint: Think of the y-axis as not the diameter of the circle, but rather a
chord of the circle.
Spoiler:
Show
Hint: Since the y-axis is a chord, it's perpendicular bisector will be halfway between the two coordinates given, i.e. y=0 aka the x-axis. So the circle lies on this lie. Therefore we already know that the equation of the circle is (x-a)2 + y2 = 52
3. (Original post by RMNDK)
Ah, do you see what's wrong with your circle?

Look at the radius. It's 3, but the radius stated is 5.
So this circle cannot be correct.
Spoiler:
Show
Hint: Think of the y-axis as not the diameter of the circle, but rather a
chord of the circle.
Spoiler:
Show
Hint: Since the y-axis is a chord, it's perpendicular bisector will be halfway between the two coordinates given, i.e. y=0 aka the x-axis. So the circle lies on this lie. Therefore we already know that the equation of the circle is (x-a)2 + y2 = 52
Thanks!
4. think about reflections in the y axis

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