👉 Isocline, also known as a surface normal line or a boundary line, in mathematics is a line that divides an object into two halves. In other words, it is a line that intersects both boundaries of an object at the same point. Example: 1. A circle with radius r has an isocline passing through its center. 2. The surface normal line to a curve at a point p on the curve passes through the point (a, b) where a and b are points