1. The problem asks for the length of line segment AB. 2. To find the length of a line segment between two points $A(x_1, y_1)$ and $B(x_2, y_2)$ in the coordinate plane, we use the distance formula: $$d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$$ 3. This formula comes from the Pythagorean theorem, where the difference in x-coordinates and y-coordinates form the legs of a right triangle, and the distance is the hypotenuse. 4. To proceed, we need the coordinates of points A and B. Without these, we cannot calculate the length. 5. Please provide the coordinates of points A and B to continue with the calculation.