Thursday, March 10, 2011

Rules of Circle Geometry

The circle is the most fascinating shape in mathematics. The circle is a locus of all the points that are the same distance from one point.

There are twelve rules in circle geometry

  1. Equal arc/chord subtend equal angles at the centre. Equal angles stand on an equal arc/chord.
  2. Equal chords are equal distance from the centre. Chords that are equal distance from the centre are equal.
  3. The line from the centre of a circle to the centre of a chord is perpendicular to the chord. A perpendicular line from the chord to the centre bisects the chord.
  4. The angle at the centre is twice the angle standing on the same chord/arc.
  5. Angles on the same arc are equal.
  6. Angles on a semi-circle is 90°
  7. Cyclic Quadrilaterals are quadrilaterals where all four corners lie on a circle. The opposite angles of cyclic quadrilaterals are supplementary.
    x+y=180°
  8. The angle between the radius and a tangent is 90°
  9. Tangents drawn from an external point are equal.
  10. Two chords or secants (AB and CD) intersecting at X, then AX.BX = CX.DX
  11. A secant and a tangent (ABX and CX) intersecting at X, then AX.BX=CX^2

  12. The angle between a chord and a tangent is equal to the angle in the alternate segment.
Hope you have learnt something.

38 comments:

  1. Nice Post, Major properties of circle at one place..
    You deserve more members (::respect::)

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    Replies
    1. So helpful Thank You

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    2. GREAT JOB BUDDY!THOSE STUDENT ALL OVER THE EARTH WITH COMPROMISED LECTURERS AND/OR THOSE UNABLE TO IMPART, NOW HAVE HOPE AND A SOLID FOUNDATION IN CIRCLE GEOMETRY

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    3. shutup im trying to study for my exam. your mouth is bigger than you mum when i do her good. her mouth is bigger than your pp. The only thing that is bigger than her mouth is your anus

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  2. Very helpful thanks, these notes are great for my class.

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  3. Thanks !!!, Test Tomorrow

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  4. Here is simple and exact definition of circle, The circumference of a circle is same as the perimeter that is the distance around the outer edge. The formula of circumference is = 2 pi r (pi's symbol).
    where r = the radius of the circle and pi = 3.14(Approx)

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  5. This is rubbish
    Wasted 5 seconds of my life

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  6. I agree with that guy you wasted my precious time!

    ReplyDelete
    Replies
    1. Well, no-one asked you to read it. :)

      Very helpful thankyou!

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    2. No, you wasted your time by writing - don't blame the dog for what you stepped in (and no, I don't mean this is shit. It's a very helpful summary.)

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  7. Can you do more rules?

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  8. SUPER,VERY HELPFULL

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  9. what does the 10nth property mean exactly? btw very helpful thnx!

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  10. Extremely helpful! I'm a grade 11 learner and I have learnt quite abit. Thanks!

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  11. how does the pythagores threom fit into these subject? is it c2=b2+a2

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    Replies
    1. Yas. A squared plus B squared = C squared

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    2. Triangles allow us to find the lengths of certain chords with a circle given we have 2 of the lengths of a chord. The theorem is a^2+b^2=c^2 where c is the hypotenuse

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    3. Oh yes, this guys are smart.

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  12. Thank you very much for the help :) continue the great work

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  13. Wow! haha thanks so much for the tips! Now I know I wont be struggling with circles! haha

    Oh an side note: You should really consider being a mathematician because I can see those maths skills pulling up the tuition!

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  14. this is good dont be so rude

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  15. very helpfull 4 my class thanks alot

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