Wednesday, February 26, 2020

Dynamic Geometry 1454: Intersecting Circles, Perpendicular Lines, Cyclic Quadrilateral

Interactive step-by-step animation using GeoGebra. Post your solution in the comment box below.
Level: Mathematics Education, High School, Honors Geometry, College.

Details: Click on the figure below.

Dynamic Geometry 1454: Intersecting Circles, Perpendicular Lines, Cyclic Quadrilateral Using GeoGebra.

8 comments:

  1. Let AOH cut circle O at X

    < XBD and < DBA are complementary angles
    But < XBD = < HAE and < DBA = < HEA

    Hence < HAE and < HEA are complementary and the result follows

    Sumith Peiris
    Moratuwa
    Sri Lanka

    ReplyDelete
    Replies
    1. Sumith - Could you please care to explain how XBD and DBA are complimentary

      -Pulliwaya

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    2. They add upto < XBA which is 90 degrees since XA is a diameter of Circle O

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    3. Thank you for the response sir. My bad I imagined X on big circle and hence the confusion.

      -Pulliwaya

      Delete
  2. https://photos.app.goo.gl/Uhb23htgvw5KE5q69

    Connect CD, OQ, OD and QD
    Let F is the midpoint of CD
    In circles O and Q we have ∠ (CAD)= ∠ (QOD) and ∠ (ACD)= ∠ (OQD)
    So Triangle CDA similar to QDO ( case AA)
    So ∠ (QDF)= ∠ (ODA)= ∠ (OAD)
    On circle Q we have ∠ (CDE)= ∠ (FQD)
    So triangle FQD similar to HEA (case AA)
    So ∠ (AHE)= ∠ (DFQ) = 90 degrees

    ReplyDelete
    Replies
    1. shouldn't line 6 read "on circle Q we have <(CED)=<(FQD)?

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    2. Yes, You are right .See link below for detail .
      https://photos.app.goo.gl/47JzfogMBJ6stvkUA

      Delete