Prove that ##AE=2BC## -Deductive Geometry

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The discussion revolves around proving the geometric relationship ##AE=2BC## within a cyclic quadrilateral. Participants analyze angles and relationships between triangles, specifically focusing on the similarity of triangles ##DCA## and ##BEA##. There is contention regarding whether point ##O##, the center of the circle, lies on line ##BD##, which affects the proof's validity. Some contributors argue that the textbook may contain an error, suggesting the correct statement should be ##AB=2BC## instead. The conversation highlights the complexity of geometric proofs and the necessity of using circle properties and congruency in the analysis.
  • #51
chwala said:
Kindly find my rejoinder...sorry am a bit busy had to scribble my response.
I have made use of similarity (on the diagram) as is suggested...and I still cannot see how ##BC= EB##.
That ##BC=EB## does not come from similarity of triangles. It comes from the fact that chord ##BC## and chord ##EB## each subtend inscribed angles of equal measure, namely ##\angle BDC## and ##\angle EDB## .

1665371287679-png.png


Steve beat me to it !.
 
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  • #52
anuttarasammyak said:
The essence of the problem is
AC/CD=AE/BC
coming from same arc lengths and similarity of triangles.
Or ##\triangle EOB \equiv \triangle COB## instead of same arc lengths, if you prefer.
1665610795201.png
 
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  • #53
...just going through my posts...this was a nice one...just to remember how i understand it in the near future; i reflected ##AE## on the supposedly mirror line ##AC##, it then follows that;

##\dfrac{AE}{BE}=\dfrac{AC}{CD}##

##\dfrac{AE}{BC}=\dfrac{AC}{CD}##

We are given; ##AC=2CD##

##\dfrac{AE}{BC}=\dfrac{2CD}{CD}##

##\dfrac{AE}{BC}=2##

##⇒AE=2BC##.
 
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