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Math Help - Circle geometry -2 problems

  1. #1
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    Circle geometry -2 problems

    And



    I'm having problems figuring these two problems out. Thanks.
    Last edited by kurdupel; December 3rd 2008 at 12:15 PM.
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  2. #2
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    Hello, kurdupel!



    Theorem: If the opposite angles of a quadrilateral have a sum of 180,
    . . . . . . . the quadrilateral is cyclic.



    The sum of the interior angles of any quadrilateral is 360.

    Angle B and C are right angles: . \angle B + \angle C \:=\:180^o

    That leaves 180 for angles O and A: . \angle O + \angle A \:=\:180^o

    Therefore, ABOC is a cyclic quadrilateral.





    Theorem: Tangents to a circle from an external point are equal.

    Hence: the two tangents from A are both 10 units long,
    . - . . . the two tangents from B are both 12 units long,
    . - . . . . . . etc.

    Got it?

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  3. #3
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    Thanks a lot I appreciate it.
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