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Euclid Geometry: Seeking for a simpler geometric solution



The Next CEO of Stack OverflowCongruent parts of trianglesFound a New Golden Ratio Construction with Equilateral Triangle, Square, and Circle. Geometric/Trigonmetric proof?Proof in Geometry. Is this solution correct?What is a geometric construction corresponding to elliptic curve addition for Sharygin-isosceles triangles?Problem about angle in isosceles triangleInscribing rhombus in a triangle's angle in only eight compass-and-straightedge stepsIn the figure, prove that points D, M and P are collinear.Angle in a 80-80-20 triangleIs there a proof of this question through Napoleon's theorem?Find an angle in a geometric figure (given) considering triangles










1












$begingroup$


The problem:



enter image description here



Answer:




Extend $AC$ to the side of $C$, such that $BC=CE$. Then, construct the
equilateral triangle $BEF$. Triangles $CAB$ and $EFC$ are congruent,
thus $AC=BE$. Now, observe that $AC=DE$, thus $BE=DE$. It follows that
$triangle BED$ is isosceles, thus $angle EDB=80$.




enter image description here



I was given this problem. The provided construction is smart, but I have a feeling that there should be a simpler non-trigonometric approach. Can anyone think of one?










share|cite|improve this question









$endgroup$
















    1












    $begingroup$


    The problem:



    enter image description here



    Answer:




    Extend $AC$ to the side of $C$, such that $BC=CE$. Then, construct the
    equilateral triangle $BEF$. Triangles $CAB$ and $EFC$ are congruent,
    thus $AC=BE$. Now, observe that $AC=DE$, thus $BE=DE$. It follows that
    $triangle BED$ is isosceles, thus $angle EDB=80$.




    enter image description here



    I was given this problem. The provided construction is smart, but I have a feeling that there should be a simpler non-trigonometric approach. Can anyone think of one?










    share|cite|improve this question









    $endgroup$














      1












      1








      1


      1



      $begingroup$


      The problem:



      enter image description here



      Answer:




      Extend $AC$ to the side of $C$, such that $BC=CE$. Then, construct the
      equilateral triangle $BEF$. Triangles $CAB$ and $EFC$ are congruent,
      thus $AC=BE$. Now, observe that $AC=DE$, thus $BE=DE$. It follows that
      $triangle BED$ is isosceles, thus $angle EDB=80$.




      enter image description here



      I was given this problem. The provided construction is smart, but I have a feeling that there should be a simpler non-trigonometric approach. Can anyone think of one?










      share|cite|improve this question









      $endgroup$




      The problem:



      enter image description here



      Answer:




      Extend $AC$ to the side of $C$, such that $BC=CE$. Then, construct the
      equilateral triangle $BEF$. Triangles $CAB$ and $EFC$ are congruent,
      thus $AC=BE$. Now, observe that $AC=DE$, thus $BE=DE$. It follows that
      $triangle BED$ is isosceles, thus $angle EDB=80$.




      enter image description here



      I was given this problem. The provided construction is smart, but I have a feeling that there should be a simpler non-trigonometric approach. Can anyone think of one?







      euclidean-geometry






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Mar 28 at 9:54









      blackenedblackened

      485413




      485413




















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