Correlation as a Geometric Mean
Drag points A, B, C, D, and E. The points A', B', C', D', and E' will move in response (these points are of the form (y,x) ). The correlation coefficient is the geometric mean of the slopes of the respective LSRLs.
proof of pythagorean-9
Orthocenter of a Triangle
sin, cos, tan helper
Circumcircle or Circumscribed Circle
Upper and Lower Sum or Riemann Sum