👉 The term "unrectifiable" refers to a shape that is not fully enclosed by its boundary, such as an ellipse or circle. In geometry, an ellipse is defined as a curve whose length of major and minor axes are proportional to each other, and it can be described in two dimensions using the equation x2/a2 + y2/b2 = 1, where (a, b) are the semi-major and semi-minor axes respectively. A circle is also an ellipse with its