👉 Countercross is a mathematical operation in linear algebra and geometry. It involves finding the number of intersections between two lines or planes, given their directions (a,b,c,d). In other words, it's used to determine how many points are on one plane that aren't on the other plane. For example: Two lines: x - 2y + z = 1 and 3x - y + 2z = 0 Intersection point: (-1, 4,