The cool part about this is that you can see the control points of the two split curves in this diagram. The original control points are the bottom edge of the triangle. The left split is the left edge of the triangle, and the right split is the right edge of the triangle.
I found a picture of the ‘lerp tree’ that might help even more: https://www.researchgate.net/figure/De-Casteljau-algorithm-t...
The cool part about this is that you can see the control points of the two split curves in this diagram. The original control points are the bottom edge of the triangle. The left split is the left edge of the triangle, and the right split is the right edge of the triangle.