Geometry Tutorial #5 -Lengths and Ratios (Theory)

#IMO​ #Geometry #MathOlympiad​
In this video we discuss the third chapter from EGMO book “Lengths and Ratios”. We learn many ideas including (law of sines, Ratio lemma, Ceva’s theorem, Menelaus’s theorem, Centroid division, and finally homothety with nine-point circle).
00:00 Intro
1:11 Extended law of sines
8:23 Ratio lemma
13:39 Ratio of areas
19:45 Ceva’s theorem
34:54 Menelaus’s theorem
42:52 Centroid and medial triangle
49:13 Homothety
01:07:54 Summary
Thanks to Arc for desigining the thumbnail.
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