MINI #22 - GEOMETRY/30-60-90 RIGHT TRIANGLES Plane Geometry Video by Art of Problem Solving's Richard Rusczyk.
MINI #8 - GEOMETRY/AUXILIARY LINES & SPECIAL RIGHT TRIANGLES Plane Geometry Video by Art of Problem Solving's Richard Rusczyk.
MINI #88 - MORE 30-60-90 RIGHT TRIANGLES Algebraic Expressions and Equations Plane Geometry Video by Art of Problem Solving's Richard Rusczyk.