Sunday, May 21, 2023

Geometry Problem 1540: Solving for the Length of Chord in a Circle: Analyzing Intersections and Given Values

Geometry Problem 1540. Post your solution in the comment box below.
Level: Mathematics Education, K-12 School, Honors Geometry, College.

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Geometry Problem 1540: Solving for the Length of Chord in a Circle: Analyzing Intersections and Given Values

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4 comments:

  1. Draw the common tangent XCY at C

    OG & BC are both perpendicular to AC, so OG//BC

    <AFC = B = <XCY = B = <GOC = <GOA = <ACE
    Hence AC is a tangent to circle FEC at C

    So AE. AF = AC^2
    Therefore AC^2 = 3 X 16
    AC = V48 = 4V3

    Sumith Peiris
    Moratuwa
    Sri Lanka

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  2. https://photos.app.goo.gl/wYT97Ju9ijb1Ww9a6

    Connect OG and FC
    Since AB= 2OC => G is the midpoint of AC and OG is the bisector of angle AOC
    We have ^(AFC)=^(AOG)=^(ACD)= u
    Triangle AEC similar to ACF ( case AA)
    So AE/AC=AC/AF
    AC^2=AC.AF= 48 and AC= 4.sqrt(3)

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  3. We can use the solution of triangles take ∠BAC = θ , ∠AED = ɣ, AC = x and radius = r;
    then by property of circle ∠BOC = 2θ
    Apply sine rule in ▵OAC which is an isosceles triangle,
    sin(2θ)/x=sin(θ)/r
    apply sine rule in ▵BAF;
    sin(ɣ)/16=1/2r
    apply sine rule in ▵DAE;
    sin(ɣ)/(r/2)=1/3
    ∴sin(ɣ)=r/2
    ∴r=√(48)
    and after further calculations θ=60°
    ∴x=√(48)=4√3

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