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Maths - Circle Theorems

  1. Apr 24, 2005 #1

    I am really confused with circle theorems, attached is a diagram and I need to find out ABC and CBO.

    I have worked out that angle ACB is x degrees, and also know that angle OAC is equal to angle OBC.

    But I don't know how to work out the what either are



    Attached Files:

  2. jcsd
  3. Apr 24, 2005 #2
    Is this something to do with opposite angles on a cyclic quadratic add up to 180?
  4. Apr 24, 2005 #3
    If youcan post it on the web somewhere, we'd be able to see it before tomorrow. It has to be pre approved.
  5. Apr 24, 2005 #4
  6. Apr 24, 2005 #5
    Arc ABC? Angle ABC? You didnt label this angle.

    Do you know anything specific about the inscription of the triangle in the circle? I want to say that the arcs between A B and C are 120 degrees, but I can't tell if thats whatits supposed to be.
  7. Apr 24, 2005 #6
    Find in terms of X, expressions for the angles:

    - ABC
    - CBO

    The points A,B, and C lie on the centre circle O.
  8. Apr 24, 2005 #7
    Since AC = BC, the triangle ABC is isosceles, and angles ABC and BAC are equal. The sum of all three angles is 180.
    Where y is angle ABC
    180 = 2y+x
    y = 90-x/2

    Do you have the answer?
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