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Math Help - Help with angles?

  1. #1
    Newbie
    Joined
    Apr 2010
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    4

    A couple questions (angles, lengths + measures)

    Hey! These two questions are stumping me... so I figured I'd come here for some help.

    1.) Circle with centre O, CE tangent at D, ∠AOD= 100 , ∠BAD= 48. Find and explain your answers.

    Here's an image I drew up: http://i50.tinypic.com/eq44t4.png

    And these are the things I need answers for:

    a) ∠ODE
    b) ∠CDB
    c) ∠BOD
    d) ∠OBD
    e) ∠ADB

    -----

    2.) Circle with diameter TD and tangents AB, BC, and CA
    AR= 5 cm
    BS= 9 cm
    CS= 17.5 cm

    --- ---
    AC ┴ AB

    Here's a drawing I did of it: http://i49.tinypic.com/2z86bk5.png

    Find the numerical value of each of the following:
    a) length of AT
    b) measure of angle TRD
    c) length of RT
    d) measure of line segment TD
    e) length of AB


    Thank you SOO SOOOO much in advance! I REALLY appreciate it!
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  2. #2
    Super Member
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    Dear Shnub,

    Let me give you some ideas,

    For the first question, notice that traingle AOD is an isosceles traingle(since OA=OD). Since A\hat{O}D is given you could find O\hat{A}D~and~O\hat{D}A

    Afterwards using the given angle B\hat{A}D=45^O you could find B\hat{A}O

    Similarly you could find all angles considering the isosceles traingles, AOB and BOD
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  3. #3
    Super Member
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    Nov 2007
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    Have you calculated angle OAD as suggested by first reply. If so just proceed to triangles AOB and OBD.
    In second problem look up the property of tangents to a circle from an external point.

    bjh
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