Hey there! Sign in to join this conversationNew here? Join for free

Circle Geometry Question Watch

Announcements
    • Thread Starter
    Offline

    2
    ReputationRep:
    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: Name:  image.jpg
Views: 46
Size:  470.0 KB
    Offline

    3
    ReputationRep:
    (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: Name:  image.jpg
Views: 46
Size:  470.0 KB

    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
    • Thread Starter
    Offline

    2
    ReputationRep:
    (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!
    Offline

    15
    ReputationRep:
    think about reflections in the y axis
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Should Spain allow Catalonia to declare independence?
    Useful resources

    Make your revision easier

    Maths

    Maths Forum posting guidelines

    Not sure where to post? Read the updated guidelines here

    Equations

    How to use LaTex

    Writing equations the easy way

    Student revising

    Study habits of A* students

    Top tips from students who have already aced their exams

    Study Planner

    Create your own Study Planner

    Never miss a deadline again

    Polling station sign

    Thinking about a maths degree?

    Chat with other maths applicants

    Can you help? Study help unanswered threads

    Groups associated with this forum:

    View associated groups
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.