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Free video lessons covering olympiad geometry, key theorems, and AMC/CEMC problem walkthroughs — taught by Dr. Daniel Deaconu.

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Olympiad Geometry

The Circumscribed Circle
Geometry
The Circumscribed Circle
Circumradius · Triangle Geometry
The Bisector Theorem
Geometry
The Bisector Theorem
Angle Bisector · Ratio of Sides
Heights Intersect
Geometry
Heights Intersect – The Orthocenter
Altitudes · Orthocenter Proof
OGH collinear Part 1
Geometry
O, G, H are Collinear – Part 1
Euler Line · Circumcenter, Centroid, Orthocenter
OGH collinear Part 2
Geometry
O, G, H are Collinear – Part 2
Euler Line · Circles
Heights are angle bisectors in the orthic
Geometry
Heights are Angle Bisectors in the Orthic Triangle
Orthic Triangle · Reflections
Midpoints on the orthic circle
Geometry
Midpoints are on the Orthic Circle
Nine-Point Circle · Midpoints
Three more points on the 9 point circle
Geometry
Three More Points on the Nine-Point Circle
Nine-Point Circle · Feet of Altitudes
Menelaus Theorem
Geometry
Menelaus' Theorem
Collinearity · Transversals
Stewart's Theorem
Geometry
Stewart's Theorem
Cevians · Triangle Side Lengths

Competition Problems

ARML solved P2
ARML
ARML Problem 2 – Solved
American Regions Mathematics League
Cayley 2016 Problem 17
CEMC
Cayley 2016 – Problem 17
University of Waterloo · Grade 10
AMC 10B 2006 Problem 15
AMC 10
AMC 10B 2006 – Problem 15
American Mathematics Competition
AMC 10A 2007 Problem 14
AMC 10
AMC 10A 2007 – Problem 14
American Mathematics Competition
AMC 10B 2007 Problem 17
AMC 10
AMC 10B 2007 – Problem 17
American Mathematics Competition

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