All Triangles are Equilateral
Interactive construction of Numberphile's "All Triangles are Equilateral" proof https://www.youtube.com/watch?v=Yajonhixy4g Drag A,B,C to adjust triangle. Measurements of BB*, CC*, and the two pairs of equal-length line segments are labeled.
Drag the points. Can you get both B* and C* both inside or both outside the triangle at the same time?