MINI #54 - SIMILAR TRIANGLES Plane Geometry Proportional Reasoning Video by Art of Problem Solving's Richard Rusczyk.
MINI #62 - SOLVING COUNTING PROBLEMS USING CASES Probability, Counting and Combinatorics Video by Art of Problem Solving's Richard Rusczyk.
MINI #67 - OPTIMIZATION PROBLEMS Problem Solving (Misc.) Video by Art of Problem Solving's Richard Rusczyk.
MINI #90 - EVEN MORE ANALYTIC GEOMETRY Coordinate Geometry Video by Art of Problem Solving's Richard Rusczyk.
MINI #99 - CONDITIONAL PROBABILITY Probability, Counting and Combinatorics Video by Art of Problem Solving's Richard Rusczyk.